WO2005002522A2 - Compositions and methods for treating tissue ischemia - Google Patents

Abstract

The present invention generally provides methods for preventing or treating tissue ischemia using CXCR4 antagonists. In one embodiment, the methods include administering to a mammal a therapeutically effective amount of a particular bicyclic polyamine to elevate peripheral blood EPCs. The invention has a wide spectrum of applications including reducing or eliminating tissue ishemica associated with a myocardial infarct (heart attack).

Description

COMPOSITIONS AND METHODS FOR TREATING TISSUE ISCHEMIA

FIELD OF THE INVENTION This application claims the benefit of U.S. Provisional Application Serial No. 60/484,052, filed June 30, 2003, the entire contents of which are hereby incorporated by this reference.

FIELD OF THE INVENTION The present invention relates to methods for preventing or treating tissue ischemia and related conditions. In one aspect, the invention provides methods for treating tissue ischemia by administrating to a mammal a therapeutically effective amount of at least one CXCR4 antagonist. The invention has a wide spectrum of useful applications including treating tissue ischemia associated with an acute myocardial infarction .

BACKGROUND OF THE INVENTION There have been reports that endothelial progenitor cells (EPCs) can be isolated from peripheral blood, are augmented in response to certain cytokines and/or tissue ischemia, and home to as well as incorporate into sites of neovascularization (Asahara T. et al (1997) Science 275:964-967; Asahara T. et al. (1999) CircRes. 85:221-228; Takahashi T. et al. (1999) Nat Med. 5:434-438; Asahara T et al. (1999) EMBOJ. 18:3964-3972; Kalka C. et al.(2000) Circ Res. 86:1198-1202; Kalka C. et al. (2000) Ann. Thorac. Surg. 70:829-834; Shi Q. et al. (1998) Blood 92:362-367; Hatzopoulos A.K. et al. (1998) Development 125:1457-1468; Gunsilius E. et al. (2000) Lancet 355:1688-1691; Gehling U.M. et al. (2000) Blood 95:3106-3112; Crosby J.R. et al. (2000) CircRes. 87:728-730; Moldovan N.I. et al. (2000) Circ Res. 87:378-384; Murohara T. et al. (2000) J. Clin. Invest. 105:1527-1536). Such cells have been shown to incorporate into sites of neovascularization (formation of new blood vessels) in adult mammals. This observation is consistent with the notion of postnatal vasculogenesis. Some studies have also shown that functional recovery after myocardial infarction is enhanced if the formation of new vessels is augmented. Recently, EPCs have been investigated as therapeutic agents; in these studies of "supply-side angiogenesis," EPCs harvested from the peripheral circulation have been expanded ex vivo and then administered to animals with limb (Kalka C. et al.

(2000) Proc. Natl. Acad. Sci. USA 97:3422-3427) or myocardial (Kawamoto A. et al.

(2001) Circulation 103: 634-637) ischemia to successfully enhance neovascularization. Physiological evidence of neo vascular function in these preclinical animal models includes a high rate of limb salvage and improvement in myocardial function.

The feasibility of using gene therapy to enhance angiogenesis has received recognition. For example, there have been reports that angiogenesis can facilitate treatment of ischemia in a rabbit model and in human clinical trials. Particular success has been achieved using NEGF-1 administered as a balloon gene delivery system. Successful transfer and sustained expression ofthe NEGF-1 gene in the vessel wall subsequently augmented neovascularization in the ischemic limb (Takeshita, et al., Laboratory Investigation, 75:487-502 (1996); Isner, et al, Lancet, 348:370 (1996)). In addition, it has been reported that direct intramuscular injection of DΝA encoding NEGF-1 into ischemic tissue induces angiogenesis, providing the ischemic tissue with increased blood vessels (Tsurumi et al., Circulation,94(12):32Sl- 3290 (1996)).

Alternative methods for promoting angiogenesis are desirable for a number of reasons. For example, it is believed that native endothelial progenitor cell (EPC) number and/or viability decreases over time. Thus, in certain patient populations, e.g., the elderly, EPCs capable of responding to angiogenic proteins maybe limited. Also, such patients may not respond well to conventional therapeutic approaches.

There have been reports that at least some of these problems can be reduced by administering isolated EPCs to patients and especially those undergoing treatment for ischemic disease. However, this suggestion is believed to be prohibitively expensive as it can require isolation and maintenance of patient cells. Moreover, handling of patient cells can pose a significant health risk to both the patient and attending personnel in some circumstances.

Granulocyte macrophage colony stimulating factor (GM-CSF) has been shown to exert a regulatory effect on granulocyte-committed progenitor cells to increase circulating granulocyte levels (Gasson, J.C., Blood 77:1131 (1991). In particular, GM-CSF acts as a growth factor for granulocyte, monocyte and eosinophil progenitors.

Administration of GM-CSF to human and non-human primates results in increased numbers of circulating neutrophils, as well as eosinophils, monocytes and lymphocytes. Accordingly, GM-CSF is believed to be particularly useful in accelerating recovery from neutropenia in patients subjected to radiation or chemotherapy, or following bone marrow transplantation. In addition, although GM- CSF is less potent than other cytokines, e.g., FGF, in promoting EC proliferation, GM-CSF activates a fully migrating phenotype. (Bussolino, et al., J. Clin. Invent., 87:986 (1991).

Accordingly, it would be desirable to have methods for modulating vascularization in a mammal and especially a human patient. It would be particularly desirable to have methods that increase EPC mobilization and neovascularization (formation of new blood vessels) in the patient that do not require isolation of EPC cells.

Accordingly, it would be desirable to have methods for modulating EPC mobilization, particularly to assist neovascularization. It would be especially desirable to have methods that increase EPC mobilization and neovascularization that do not require prior isolation of EPC cells.

SUMMARY OF THE INVENTION The present invention generally relates to methods for preventing or treating tissue ischemia. In one aspect, the invention provides methods for treating tissue ischemia that include administering to a mammal a therapeutically effective amount of at least one CXCR4 antagonist. Methods ofthe invention can be used alone or in combination with other agents such as those that promote the proliferation of endothelial progenitor (EPC) cells. The invention has many important uses including treating tissue ischemia associated with acute myocardial infarction (AMI).

We have found that particular cyclic polyamines can be used as effective CXCR4 antagonists. More specifically, we have learned that use of such antagonists desirably enhances presence of circulating EPCs in a subject mammal. Without wishing to be bound to theory, it is believed that the increase in EPCs can help to promote neovascularization, thereby reducing the symptoms of or in some instances eliminating potentially life-threatening consequences of tissue ischemia. Practice of the invention can be implemented before, during or after diagnosis of ishemia or a related condition with use after detection of tissue ischemia being generally preferred.

In one embodiment, the present methods can be used during or after AMI to enhance recruitment and incorporation of EPCs into sites where new vasculature is needed. Examples of such sites include those associated with damage to the myocardium and related tissue including supporting vasculature. In this embodiment, preferred practice ofthe invention reduces or eliminates many symptoms associated with AMI including, but not limited to, myocardial fibrosis and reduced left ventricle (LN) dilation. It is thus an object ofthe invention to provide effective treatments methods that include administering the CXCR4 antagonists to promote EPC mobilization and enhance neovascularization at or near sites of ischemia. In embodiments in which AMI is to be treated, such sites will often include peri-infarct myocardium.

More generally, the present invention provides a method for preventing or treating tissue ischemia that includes administering to a subject at least one optionally substituted cyclic polyamine as provided herein. A preferred cyclic polyamine is known to or can be shown to antagonize activity ofthe CXCR4 receptor. More particular cyclic polyamine antagonists feature about four or less cyclic polyamine groups, generally less than about three of such groups being preferred for most embodiments. More preferred CXCR4 antagonists are optionally substituted bicyclic polyamines in which each polyamine group is spaced from the other by a specific linker. A preferred linker includes an optionally substituted aryl group comprising about six carbon atoms. Particular CXCR4 antagonists are described below.

Acceptable CXCR4 antagonists for use with the invention preferably induce EPC mobilization according to one or more assays as provided herein. Such antagonists also desirably assist neovascularization in the subject, particularly at or near sites impacted by tissue ischemia. By the term "induction" is meant enhancing EPC mobilization and preferably also facilitating formation of new blood vessels in ischemic tissue when compared to a suitable control (ie. without administration ofthe antagonist). By "EPC mobilization" is meant a significant increase in the number of peripheral blood EPCs as determined by assays disclosed herein.

More particular methods according to the invention include administering to the mammal a therapeutically effective amount of a CXCR4 antagonist under conditions sufficient to elevate peripheral blood EPC counts when compared to a control in which the antagonist has not been employed. Preferably, the amount of administered CXCR4 antagonist is also capable of increasing neovascularization in the ischemic tissue when compared to the control. Even more preferably, the therapeutically effective amount ofthe CXCR4 antagonist is sufficient to help maintain a detectable level of ishemic tissue function in the mammal and in some cases essentially preserving that function at or near normal levels as determined by the assays disclosed herein. A variety of methods for detecting and quantifying the blood EPC count, neovascularization and ischemic tissue function are known and include those assays discussed below and in the examples which follow.

In a particular embodiment ofthe method, the .enhancement in EPC mobilization and typically also the increase in peripheral blood EPC count is at least about 20% and preferably from between 50% to 500% as determined by what is referred to herein as a "standard cultured EPC assay". That assay generally detects and quantifies EPC number and is described in detail below.

In another particular embodiment, the amount of administered CXCR4 antagonist is sufficient to preserve the function of at least part ofthe myocardium in the subject, usually a mammal such as a primate, that has suffered or is suffering from AMI. Methods for detecting and quantifying heart function include conventional methods known in the field such as echocardiographic and hemodynamic measurements, particularly ventricle dilation (systolic and/or diastolic), fractional shortening, or both. Other suitable tests include conventional hemodynamic measurements of systolic pressure, end-diastolic pressure, +dP/dt, and -dP/dt.

Additionally suitable amounts of administered CXCR4 antagonist include amounts sufficient to increase recruitment of EPCs to and/or increase capillary density in ischemic tissue by at least about 20% and preferably from between 50% to 500% as determined by what is referred to herein as a "standard hind limb ischemia assay" as discussed below.

As will become more apparent from the discussion and Examples which follow, the mvention is flexible and can be used as the sole therapy or in combination with other methods, agents or therapies for modulating EPC proliferation. In one embodiment, the invention includes methods for treating tissue ischemia in a mammal in which the therapeutically effective amount ofthe CXCR4 antagonist is co- administered with at least one other agent that promotes EPC proliferation. It is believed that co-administration ofthe CXCR4 antagonist and the agent positively impacts neovascularization in the ischemic tissue ofthe mammal by providing additive or synergistic effects when compared to administration ofthe CXCR4 antagonist alone. A preferred agent for promoting EPC proliferation includes those recognized endothelial cell mitogens. Specific agents are discussed below.

In another invention embodiment, one or a combination ofthe CXCR4 antagonists is administered to a subject in need of such treatment in conjunction with one or more identified methods for preventing or treating tissue ischemia. Such methods include, but are not limited to, surgical procedures such as angioplasty, and conventional anti-clotting therapies such use of one or more of an anti-thrombolytic or anti-coagulants known in the field.

In another aspect, the invention provides a pharmaceutical product that is preferably formulated to modulate and especially to induce EPC mobilization in a subject, hi one embodiment, the product includes a therapeutically effective amount of a CXCR4 antagonist that is preferably suitable for administration to a mammal and particularly a human patient in need of such treatment. In a specific embodiment, the product is provided as a sterile formulation and can optionally include a therapeutically effective amount of an agent that promotes EPC proliferation. Alternatively, the CXCR4 antagonist and the agent that promotes EPC proliferation can be provided as physically separate pharmaceutical formulations. If desired, the pharmaceutical formulation can be provided in a kit or related format.

Other aspects ofthe invention are disclosed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a graph ofthe change in mononuclear cell (MNC) and endothelial progenitor cell (EPC) numbers after a single injection of AMD-3100.

Figures 2A-2B depict the results of echocardographic measurements in mice injected with AMD-3100 after acute mycardial infarction (AMI). Figure 2A depicts the measurement of LVDd (diastolic left ventricle dilation) and LNDs (systolic left ventricle dilation). Figure 2B depicts the measurement of heart rate and fractional shortening.

Figures 3A-3C depict the results of hemodynamic measurements using a Millar catheter in mice injected with AMD-3100 after acute myocardial infarction (AMI). Figure 3A depicts the measurement of LNSP (left ventricle systolic pressure) and LNEDP (left ventricle end-diastolic pressure). Figure 3B depicts +dP/db. Figure 3C depicts -dP/dt.

Figures 4A-4B depicts the survival rate of mice injected with AMD-3100 after acute myocardial infarction (AMI).

Figures 5A-5Ddepict the results of iirimnunohistochemistry in the border zone one and two weeks after acute myocardial infarction (AMI), with or without treatment with AMD-3100. The data are representative findings using n antibody to isolectin B4. Figure 5A: AMD-3100, 1 week; Figure 5B: AMD-3100, 2 weeks; Figure 5C: control, 1 week; Figure 5D: control, 2 weeks. Figures 6A-6C depict the quantitation of capillary density at the border zone one (Figure 6 A) and two weeks (Figure 6B) after injection with AMD-3100 after acute myocardial infarction (AMI). Figure 6C depicts data for one, two, and four weeks.

Figures 7A-7C depict the decrease in left ventricle fibrosis area two weeks after AMI, with or without treatment with AMD-3100. Figure 7 A: macroscopic view, AMD-3100; Figure 7B: macroscopic view, control; Figure 7C: quantitation of % fibrosis area.

Figure 8 depicts the number of endothelial progenitor cells (EPCs) in peripheral blood one and two weeks after injection with AMD-3100 after acute myocardial infarction (AMI).

Figures 9A-9D depict the augmentation of recruitment of bone marrow derived EPCs 1 and 2 weeks after AMI, with or without treatment with AMD-3100. Figure 9 A: AMD-3100, 1 week; Figure 9B: AMD-3100, 2 weeks; Figure 9C: control, 1 week; Figure 9D: control, 2 weeks.

Figures 10A-10D depict representative findings using counterstaining 1 and 2 weeks after AMI, with or without treatment with AMD-3100, in Tie2-LacZ/BMT mice. Figure 9A: AMD-3100, 1 week; Figure 9B: AMD-3100, 2 weeks; Figure 9C: control, 1 week; Figure 9D: control, 2 weeks.

Figures 11 A-l IB depict the quantitation of X-gal positive cells (i.e., bone- marrow derived endothelial cells) present in ischemic tissue one (Figure 11 A) and two weeks (Figure 1 IB) after injection with AMD-3100 after acute myocardial infarction (AMI).

Figures 12A-12F depict representative results of fluorescence microscopy of ischemic myocardium 1 week after AMI, with or without treatment with AMD-3100. Cells were stained for BS lectin 1 and/or β-galactosidase (β-gal) to identify bone- marrow derived endothelial cells. Figure 12 A: AMD-3100, BS lectin 1; Figure 12B: AMD-3100, β-gal; Figure 12C: AMD-3100, BS lectin 1 and β-gal double stain; Figure 13D: control, BS lectin 1; Figure 12E: control, β-gal; Figure 13F: control, BS lectin 1 and β-gal double stain.

Figures 13A-13F depict representative results of fluorescence microscopy of intact myocardium 1 week after AMI, with or without treatment with AMD-3100. Cells were stained for BS lectin 1 and/or β-galactosidase (β-gal) to identify bone marrow derived endothelial cells. Figure 1313 A: AMD-3100, BS lectin 1; Figure 13B: AMD-3100, β-gal; Figure 13C: AMD-3100, BS lectin 1 and β-gal double stain; Figure 13D: control, BS lectin 1; Figure 13E: control, β-gal; Figure 13F: control, BS lectin 1 and β-gal double stain.

Figures 14A-14B depict representative 4-quadrant analysis of double positive cells between Sca-1 (x axis) and Flk-1 (y axis) for AMD3100-treated and untreated EPCs isolated from peripheral blood using FACS analysis (Figure 14A); statistical analysis also shows an increase in circulating EPCs 1 week after MI (Figure 14B).

Figures 15A-15E depict the following: Figure 15 A: Representative 4- quadrant analysis of double positive cells between Sca-1 (x-axis) and Flk-1 (y axis) for AMD3100-treated and untreated EPCs isolated from total BM cells using FACS analysis. Figure 15B: Statistical analysis shows that AMD3100 prevents decreasing EPCs in BM 1 week after MI. Figure 15C: AMD3100 upregulates expression of MMP-9 mRNA in BM mononuclear cells. Panel shows RT-PCR products for MMP- 9, MMP-2 and GAPDH. Figure 15D: Representative 4-quadrant analysis of double positive cells between Sca-1 (x axis) and Flk-1 (y axis) for AMD3100-treated and untreated EPCs isolated from total BM cells in MMP-9^"7" mice 1 week after MI by using FACS analysis. Figure 15E: Statistical analysis also shows no differences in BM EPCs 1 week after MI.

DETAILED DESCRIPTION OF THE INVENTION As discussed, the present invention provides methods for treating tissue ischemia in a subject such as a human patient. In one embodiment, the methods include administrating to the patient a therapeutically effective amount of at least one suitable CXCR4 antagonist. The antagonist can be administered alone as the sole therapeutic agent or in combination with at least one other agent, preferably one that promotes endothelial progenitor cell (EPC) proliferation. The invention has a wide spectrum of uses including preventing or reducing the severity of tissue damage after acute myocardial infarction (AMI).

As also discussed, it is an object ofthe invention to provide methods for the controlled mobilization of EPCs and to assist neovascularization. Without wishing to be bound to theory, it is believed that EPC mobilization can be assisted by blocking activity ofthe CXCR4 receptor, especially such receptors expressed in or near bone marrow tissue. Mobilization of EPCs according to the invention helps to elevate peripheral blood EPC count, thereby making more EPCs available for formation of new blood vessels. The increased availability of circulating EPCs provided by the invention is believed to promote neovascularization in a wide variety of ischemic tissues in need of treatment including, but not limited to, the myocardium. Methods ofthe mvention generally include administering to the patient a therapeutically effective amount of at least one CXCR4 antagonist e.g., less than about five of same such as one, two or three of such antagonists.

By the phrase "ischemic tissue" is meant damaged tissue having a deficiency in blood or blood vessels typically as the result of myocardial infarction, cerebrovascular ischemia, renal ischemia, pulmonary ischemia, limb ischemia, ischemic cardiomyopathy, ischemic organ (e.g., a transplanted organ) and myocardial ischemia.

Administration of one or more CXCR4 antagonists according to the invention can be as needed and may be implemented before, during or after detection of ischemic tissue in the subject. In many instances, treatment can begin if the subject is suspected to possess ischemic tissue such as after a heart attack. When administered in conjunction with an agent that promotes EPC proliferation, the CXCR4 antagonist may be administered at the same time, before, or preferably, after the agent that promotes EPC proliferation. As discussed, methods of this mvention have a wide spectrum of uses especially in the prevention or treatment of tissue damage resulting from tissue ischemia. Such tissue damage can arise as a direct result or indirectly arise from the ischemia. A particular type of tissue ischemia of interest is associated with one or more of acute myocardial infarction (referred to interchangeably herein as "myocardial infarction", "MI", "AMI", or its common name, "heart attack"), trauma, graft rejection, cerebrovascular ischemia, renal ischemia, pulmonary ischemia, ischemia related to infection, limb ischemia, ischemic cardiomyopathy, cerebrovascular ischemia, and myocardial ischemia.

It will be appreciated however that the invention is not limited to addressing these specific indications. That is, the methods provided herein are intended to enhance neovascularization of nearly any tissue, organ or physiological system in a subject mammal including those tissues and organs associated with circulatory system or the central nervous system, e.g., a limb, graft (e.g., muscle or nerve graft), or organ (e.g., heart, brain, kidney and lung). For instance, the ischemia may adversely impact heart or brain tissue as often occurs in cardiovascular disease or stroke, respectively, in which case the invention can be used to prevent or treat the ischemia afflicting those tissues.

The CXCR4 antagonist can be administered to the subject before, during or after detection of tissue ischemia in the subject. However, the invention is not tied to demonstration of such ischemia in the subject. That is, the invention methods can be employed, for instance, when the subject has experienced a myocardial infarct. Thus in one embodiment, the CXCR4 antagonist can be administered not more than about a month after detection ofthe ischemia (or after the infarct) for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, or 24 hours thereafter. However in other embodiments, more robust treatment methods may be indicated and require administering the CXCR4 antagonist to the subject during or not long after (e.g., less than a few days later including several hours after ) detection ofthe ischemia or infarct occurrence.

The methods of this mvention are suitable for tissue ischemia in a variety of animals including mammals. The term "mammal" is used herein to refer to a warmblooded animal such as a rodent, rabbit, or a primate and especially a human patient. Specific rodents and primates of interest include those animals representing accepted models of human disease including the pig, chimp, sheep, goat, horse, mouse, rat, rabbit, and monkey. Particular human patients of interest include those who have, are suspected of having, or are at risk of having ischemic tissue.

Conditions that facilitate or assist formation of ischemic tissue are known in the field and include, but are not limited to, a surgical manipulation (e.g., restenosis associated with angioplasty) or a medical condition such as AMI. Ischemic tissue is often associated with an ischemic vascular disease such as those specific conditions and diseases discussed below.

As discussed above, it has been found that particular bicyclic polyamines can be used to promote neovascularization of ischemic tissue. Without wishing to be bound by theory it is believed that preferred administration of such compounds reduces or block CXRCR4 receptor activity especially in bone marrow. Reduction or in some instances a cessation in receptor activity augments EPC mobilization from the bone marrow into the peripheral blood. In accordance with the present invention, such bicyclic polyamines are believed to function as potent CXCR4 antagonists which can be used to enhance recovery of ischemic tissue.

The term "CXCR4", as used herein, shall be understood to refer to the CXCR4 chemokine receptor, a receptor in the GPCR (G-protein coupled receptor) gene family, which is expressed by cells in the bone marrow, immune system and the central nervous system. In response to binding its ligand SDF-1 (stromal cell-derived factor- 1), CXCR4 is thought to trigger the migration and recruitment of immune cells, as well as the homing of stem cells (e.g., EPCs). The receptor is believed to enhance downstream signaling by several different pathways. As a GPCR, CXCR4 binding of SDF-1 activates G-protein mediated signaling, including downstream pathways such as ras, and PI3 kinase. PI3 kinase activated by SDF-1 and CXCR4 plays a role in lymphocyte chemotaxis in response to these signals. One endpoint of CXCR4 signaling is the activation of transcription factors such as AP-1 and chemokine regulated genes. JAK/STAT signaling pathways also appear to play a role in SDF- 1/CXCR4 signaling.

The structure ofthe human CXCRF4 receptor is known. See GenBank Accession Nos. NM_003467 and NP_003458, respectively. The nucleotide and polypeptide sequences of human SDF-1 are set forth in GenBank Accession Nos. NM_000609 and NP_000600, respectively. See Hwang, J.H. et al. (2003) J. Clin. Endocrinol. Metab. 88(1):408-416; Babcock, G.J. et al. (2003) J. Biol. Chem. 278(5):3378-3385; Barbouche, R. et al. (2003) J. Biol. Chem. 278(5):3131-3136; Adams, G.B. et al. (2003) Blood 101(1):45-51; Lapham, C.K. et al. (2002) J. Leukoc. Biol. 72(6):1206-1214; Zhou, Y. et al. (2002) J. Biol. Chem. 277(51):49481-49487; Sun, Y. et al. (2002) J. Biol. Chem. 277(51):49212-49219; Bachelder, R.E. et al. (2002) Cancer Res. 62(24),:7203-7206; Barbero, S. et al. (2002) Ann. N.Y. Acad. Sci. 973:60-69; Rey, M. et al. (2002) J. Immunol. 169(10):5410-5414; BasmacioguUari. S. et al. (2002) J. Virol. 76(21):10791-10800; Konig, R.R. et al. (2002) J. Virol. 76(21):10627-10636; Martinez-Caceres, E.M. et al. (2002) Mult. Scler. 8(5):390-395; Ode is, V. et al. (2002) J. Biol. Chem. 277(42):39801-39808; Moriuchi, M.et al. (2002) J. Infect. Dis. 186(8):1194-1197; Kollet, O. et al. (2002) Blood 100(8):2778- 2786; Libura, J. et al. (2002) Blood 100(7):2597-2606; Honczarenko, M. et al. (2002) Blood 100(7):2321-2329; Ptasznik, A. et al. (2002) J. Exp. Med. 196(5):667-678; Estes, J.D. et al. (2002) J. Immunol. 169(5):2313-2322; Farzan, M. et al. (2002) J. Biol. Chem. 277 (33):29484-29489; Fotopoulos, G. et al. (2002) Proc. Natl. Acad. Sci. U.S.A. 99(14):9410-9414; Peled, A. et al. (2002) Stem Cells 20(3):259-266; Habasque, C. (2002) Mol. Hum. Reprod. 8(5):419-425; Zhou, N. et al. (2002) J. Biol. Chem. 277(20): 17476-17485; Lu, M. et al. (2002) Proc. Natl. Acad. Sci. U.S.A. 99(10):7090-7095; Nalenzuela-Fernandez, A. et al. (2002) J. Biol. Chem. 277(18): 15677-15689; Schrader, NJ. et al. (2002) Br. J. Cancer 86(8): 1250-1256; Nguyen, D.H. and Taub, D. (2002) J. Immunol. 168(8):4121-4126; Salvucci, O. et al. (2002) Blood 99(8):2703-2711; Juffermans, N.P. et al. (2002) J. Infect. Dis. 185(7):986-989; Taichman, R.S. et al. (2002) Cancer Res. 62(6):1832-1837; Zamarchi, R. et al. (2002) Clin. Exp. Immunol. 127(2):321-330; Arthos, J. et al. (2002) Virology 292(1):98-106; Ferraro, GA. et al. (2001) AIDS Res. Hum. Retroviruses 17(13):1241-1247; Ullrich, C.K. et al. (2000) Blood 96(4):1438-1442; Poznansky, M.C. et al. (2000) Nat. Med. 6(5):543-548; Secchiero, P. et al. (2000) J. Immunol. 164(8) :4018-4024; Cheng, Z.J. et al. (2000) J. Biol. Chem. 275(4):2479- 2485; Lalani, A.S. et al. (1999) Science 286(5446):1968-1971; Sotsios, Y. et al. (1999) J. Immunol. 163(11):5954-5963; Gupta, S.K. and Pillarisetti, K. (1999) J. Immunol. 163(5):2368-2372; Klein, R.S. et al. (1999) J. Immunol. 163(3):1636-1646; Ling, K. et al. (1999) Proc. Natl. Acad. Sci. U.S.A. 96(14):7922-7927; Yasukawa, M. et al. (1999) J. Immunol. 162(9):5417-5422; Zou, Y.R. et al. (1998) Nature 393(6685):595-599; Tachibana, K. et al. (1998) Nature 393(6685):591-594; Caruz, A. et al. (1998) FEBS Lett. 426(2):271-278; Moriuchi, M. et al. (1997) J. Immunol. 159(9):4322-4329; Bleul, C.C. et al. (1996) Nature 382(6594):829-833; Choe, H. et al. (1996) Cell 85(7):1135-1148; Lu, Z.H. et al. (1995) J. Biol. Chem. 270(44):26239- 26245; Loetscher, M. et al. (1994) J. Biol. Chem. 269(l):232-237; Nomura, H. et al. (1993) Int. Immunol. 5(10):1239-1249; Jazin, E.E. et al. (1993) Regul. Pept. 47(3):247-258; Herzog, H. et al. (1993) DNA Cell Biol. 12(6):465-471; Federsppiel, B. et al. (2993) Genomics 16(3):707-712 (1993); Bleul, C.C. et al. (1996) Nature 382(6594):829-33); Cheng, Z. et al. (2000) J. Biol. Chem. 275(4):2476-2485; Dutt, P. et al. (1998) J. Immunology. 161: 3652-3658; Wang, J.F. et al. (2000) Blood 95(8):2505-13; Ling K. et al. (1999) Cell Biology 96:7922-7927; Vicente- Manzanares, M. et al.(1999) Immunology 163:4001-12; Ganju, R.K. et al. (1998) Biological Chemistry 273(36):23169-175; and Zhang, X.F. et al. (2001) Blood 97(11):3342-3348; and references cited therein.

The structure and function ofthe SDF-1 ligand is also known (also referred to herein as SDF-lα). See Glodek, A.M. et al. (2003) J. Exp. Med. 197(4):461-473; Roland, J. et al. (2003) Blood 101(2):399-406; Adams, G.B. (2003) Blood 101(1):45- 51; Sun, Y. et al. (2002) J. Biol. Chem. 277(51):49212-49219; Krug, A. et al. (2002) J. Immunol. 169(11):6079-6083; Barbero, S. et al. (2002) Ann. N.Y. Acad. Sci. 973:60-69; Nance, C.L. and Shearer, W.T. (2002) Clin. Immunol. 105(2):208-214; Libura, J. et al. (2002) Blood 100(7):2597-2606; Honczarenko, M. (2002) Blood 100(7):2321-2329; Netelenbos, T. (2002) J. Leukoc. Biol. 72(2):353-362; Farzan, M. et al. (2002) J. Biol. Chem. 277(33):29484-29489; Okabe, S. et al. (2002) Exp. Hematol. 30(7):761-766; Langford, D. (2002) J. Neuroimmunol. 127(1-2):115-126; Inngjerdingen, M. et al. (2002) Blood 99(12):4318-4325; Lee, Y. (2002) Blood 99(12):4307-4317; Peled, A. (2002) Stem Cells 20(3):259-266; Wright, N. et al. (2002) J. Immunol. 168(10):5268-5277; Nalenzuela-Fernandez, A. (2002) J. Biol. Chem. 277(18):15677-15689; Schrader, A.J. et al. (2002) Br. J. Cancer 86(8):1250- 1256; Salvucci, O. et al. (2002) Blood 99(8):2703-2711; Taichman, R.S. et al. (2002) Cancer Res. 62(6):1832-1837; Zaitseva, M. et al. (2002) J. Immunol. 168(6):2609- 2617; Casamayor-Palleja, M. et al. (2002) Blood 99(6):1913-1921; Phillips, R. and Ager, A. (2002) Eur. J. Immunol. 32(3):837-847; Tresoldi, E. et al. (2002) J. Infect. Dis. 185(5):696-700; Riabov, G.S. et al. (2002) Genetika 38(2):278-280; Lataillade, J.J. et al. (2002) Blood 99(4):1117-1129; Nanki, T. and Lipsky, P.E. (2001) Cell. Immunol. 214(2):145-154; Lathey, J.L. et al. (2001) J. Infect. Dis. 184(11):1402- 1411; Bajetto, A. et al. (2001) J. Neurochem. 77(5):1226-1236; Poznansky, M.C. et al. (2000) Nat. Med.^'6(5):543-548; Ghezzi, S. et al. (2000) Biochem. Biophys. Res. Commun. 270(3):992-996; Cheng, Z.J. et al. (2000) J. Biol. Chem. 275(4):2479-2485; Luttichau, H.R. et al. (2000) J. Exp. Med. 191(1):171-180; Lalani, A.S. et al. (1999) Science 286(5446): 1968-1971; Sotsios, Y. et al. (1999) J. Immunol. 163(11):5954- 5963; Nicente-Manzanares, M. et al. (1999) J. Immunol. 163(7):4001-4012; Kozak, S.L. et al. (1999) J. Biol. Chem. 274(33):23499-23507; Su, S.B. et al. (1999) J. Immunol. 162(12):7128-7132; Weber, K.S. et al. (1999) Mol. Biol. Cell 10(4):861- 873; Zaitseva, M.B. et al. (1998) J. Immunol. 161(6):3103-3113; Rubbert, A. et al. (1998) J. Immunol. 160(8):3933-3941; Bleul, C.C. et al. (1996) Nature 382(6594):829-833; and Shirozu, M. et al. (1995) Genomics 28(3):495-500; and references cited therein.

The term "CXCR4 antagonist", as used herein, refers to a cyclic polyamine as represented by the following general formula set forth as formula (1) below.

Z-linker-Z' (1)

Formula I wherein Z is a cyclic polyamine containing 9-32 ring members of which 3-8 are nitrogen atoms; said nitrogen atoms separated from each other by at least 2 carbon atoms, wherein said heterocycle may optionally contain additional heteroatoms besides nitrogen and/or may be fused to an additional ring system.

Z' may be embodied in a form as defined by Z above, or alternatively may be ofthe formula

-N(R)-(CR₂)_n -X wherein each R is independently H or straight, branched or cyclic alkyl (1-6C), n is 1 or 2, and

X is an aromatic ring, including heteroaromatic rings, or is a mercaptan;

A "linker" represents a bond, alkylene (1-6C) or may comprise aryl, fused aryl, oxygen atoms contained in an alkylene chain, or may contain keto groups or nitrogen or sulfur atoms.

In general, preferred embodiments of Z and Z' according to Formula I are cyclic polyamine moieties having from about 9 to about 24 carbon atoms and include from about 3 to about 5 nitrogen atoms.

Preferred cyclic polyamines in accord with the invention include the following: 1,5,9,13-tetraazacyclohexadecane; 1,5,8,11,14-pentaazacyclohexadecane; 1,4,8,11-tetraazacylotetradecane; 1,5,9-tnazacylcododecane; 1,4,7,10- tetraazacyclododecane; and the like, including such cyclic polyamines which are fused to an additional aromatic or heteroaromatic rings and/or containing a heteroatom other than nitrogen incorporated in the ring. Embodiments wherein the cyclic polyamine contains a fused additional cyclic system or one or more additional heteroatoms are described in U.S. Pat. No. 5,698,546 incorporated hereinabove by reference.

More preferred cyclic polyamines according to the invention are bicyclic molecules in which each cyclic group is spaced from the other by a convenient linker Examples include the following molecules:

3,7,ll,17-tetraazabicyclo(13.3.1)heptadeca-l(17),13,15-triene;

4,7,10,17-tetraazabicyclo(13.3.1)heptadeca-l(17),13,15-triene;

1,4,7, 10-tetraazacyclotetradecane; 1,4,7-triazacyclotetradecane; and

4,7, 10-triazabicyclo(l 3.3. l)heptadeca-l (17), 13, 15-triene.

See U.S. Pat. Nos. 5,021,409; 5,583,131; 5,698,546; 5,817,807; application Ser. No. 09/111,895 filed Jul. 8, 1998; 5,612,478; 5,756,728; 5,801,281; 6,365,583, and 5,606,053 (disclosing useful related compounds), the disclosures of which are incorporated herein by reference.

Preferred linker moieties for spacing the cyclic polyamine group include those wherein the linker is a bond, or wherein the linker includes an aromatic (aryl) moiety. Preferably, the linker is includes two C₂.₆ alkylene groups, preferably methylene moieties, that flank the aromatic group. Preferred linking groups include the methylene bracketed forms of 1,3-phenylene, 2,6-pyridine, 3,5-pyridine, 2,5- thiophene, 4,4^,-(2,2'-bipyrimidine); 2,9-(l,10-phenanthroline) and the like. A particularly preferred linker is l,4-phenylene-bis-(methylene).

An especially preferred bicyclic polyamine for use with the present invention includes a 2,2'-bicyclam; 6,6'-bicyclam group. See U.S. Pat. No. 5,583,131, and in particular 1 , 1 '- [ 1 ,4-phenylene-bis(methylene)] -bis- 1,4,8,11 -tetraazacyclotefradecane, as set forth in U.S. Pat. No. 5,021,409, and designated herein AMD-3100. AMD- 3100, a reversible, competitive inhibitor of SDF-1 α binding to CXCR4, is a white to off-white powder with a molecular weight of 502.79 Da and the empirical formula C₂₈H₅₄N₈. Its chemical structure is shown below.

The structure of AMD-3100 is shown below as Formula II.

Additional cyclic polyamines for use according to the invention include the following specific compounds: N-[ 1 ,4,8, 11-tetraazacyclotetradecanyl-l ,4-phenylenebis(methylene)]-2- aminomethyl)pyridine;

7,7'-[ 1 ,4-phenylenebis(methylene)]bis-4,7, 10, 17-tetraazabicyclo- [13.3.1]heρtadeca-l(17),13,15-triene;

7,7'-[l,4-phenylenebis(methylene)]bis-3,7,ll,17- tetraazabicyclo[ 13.3.1 ]heptadeca- 1 (17), 13 , 15-triene;

1 , l'-[ 1 ,3-phenylenebis(methylene)]-bis-l ,4,8, 11 -tetra-azacyclotetradecane;

1 , 1 '-[ 1 ,4-phenylenebis(methylene)]-bis-l ,4,8, 11 -tetra-azacyclotetradecane;

1 , 1 '-[1 ,4-phenylene-bis-(methylene)] -bis-1 ,4,7, 10-tetraazacyclotetradecane;

1 , 1 '-[ 1 ,3-phenylene-bis-(methylene)] -bis- 1 ,4,7, 10-tetraazacyclotetradecane; ll,ir-(l,2-propanediyl)bis-l,4,8,ll-tetraazacyclotetradecane;

N-[4-(l,4,7-triazacyclotefra-decane)-l,4-phenylenebis(methylene)]-2- (aminomethyl)pyridine;

N-[7-(4,7,10-triazabicyclo[13.3. l]heptadeca-l(17),13,15-triene)-l,4- phenylenebis(methylene)] -2-(aminomethy l)pyridine;

N-[7-(4,7,10,17-tetraazabicyclo[13.3. l]heρtadeca-l(17),13,15-triene)~l,4- phenylenebis(methylene)]-2-(aminomethy l)pyridine; and

N-[4-[4,7,10,17-tetraazabicyclo[13.3. l]heptadeca-l(17),13,15-triene]-l,4- phenylenebis(methylene)]-2-(aminomethyl)pyridine.

The present invention is compatible with one or a combination of different administration routes. For instance, and in one embodiment, ompounds ofthe invention may be prepared in the form of prodrugs, i.e., protected forms which release the compounds ofthe invention after administration to the subject. Typically, the protecting groups are hydrolyzed in body fluids such as in the bloodstream thus releasing the active compound or are oxidized or reduced in vivo to release the active compound. A discussion of prodrugs is foimd in Smith and Williams Introduction to the Principles of Drug Design, Smith, H. J.; Wright, 2.sup.nd ed., London (1988). Preferred cyclic polyamines for use with the invention can be readily identified by those in the field, typically by testing compounds in a what is referred to herein as a CXCR4 activity assay. Preferrred assay formats are cell-based assay. Thus a cell-based CXCR4 activity assay (referred to herein as a "standard receptor binding assay") typically includes providing a cell that expresses CXCR4, contacting the cell with stromal cell derived factor-1 (SDF-1) (or a receptor binding fragment thereof) along with the test compound. The test compound is typically assayed for its ability to antagonize SDF-1 mediated CXCR4 signaling. A test compound can also be assayed for the ability to antagonize SDF-1 binding to CXCR4 in vitro. Cyclic polyamines identified as potential CXCR4 antagonists using such assays can then be tested, for example, using methods described herein, particularly in the Examples, for the ability to mobilize EPCs into the peripheral blood circulation, for the ability to induce recruitment of bone marrow derived EPCs to sites of tissue ischemia, and/or for the ability to preserve function of ischemic tissue.

More preferred receptor antagonists ofthe invention reduce or completely block binding of SDF-1 (or a receptor binding fragment thereof) to the CXCR4 receptor, typically by at least about 25%, more preferably at least about 50% when compared to full-length SDF-1. Methods for detecting and quantifying such activity are known and include the foregoing standard receptor-binding assay.

The above-described compounds can be prepared for use with the invention as pharmaceutically acceptable equivalents such as acid addition salts, solvates, hydrates, and metal complexes thereof. Suitable acid addition salts include salts of inorganic acids that are biocompatible, including HC1, HBr, sulfuric, phosphoric and the like, as well as organic acids such as acetic, propionic, butyric and the like, as well as acids containing more than one carboxyl group, such as oxalic, glutaric, adipic and the like. Typically, at physiological pH, the compounds ofthe invention will be in the forms ofthe acid addition salts. Particularly preferred are the hydrobromides. In addition, when prepared as purified forms, the compounds may also be crystallized as the hydrates.

If desired, one or a combination ofthe foregoing cyclic polyamines can be used in combination with one or more other antagonists ofthe CXCR4 receptor. For example, see ALX40-4C, T22, and T140 (See also Scozzafava, A. et al. (2002) J Enzyme Inhib. Med. Chem. 17(2):69-76; Fujii, N. et al. (2003) Expert Opin. Investig. Drugs 12(2):185-95; Agrawal, L. et al. (2001) Expert Opin. Ther. Targets 5(3):303- 326; Pohlmann, S. and Doms, R.W. (2002) Curr. Drug Targets Meet. Disord. 2(1):9- 16; De Clercq, E. (2002) Med. Res. Rev. 22(6):531-65; Starr-Spires, L.D. and Collman, R.G. (2002) Clin. Lab. Med. 22(3):681-701).

As described elsewhere herein, a CXCR4 antagonist can be administered in conjunction with an agent that promotes the proliferation of EPCs. The use of such proliferation-promoting agents provides a larger pool of EPCs that can be mobilized from the bone marrow. Agents that promote the proliferation of EPCs can be of any type, including small molecules, peptides, peptidomimetics, nucleic acids, or other types of compounds or agents.

In one embodiment, an agent that promotes the proliferation of EPCs (also referred to herein as an "EPC proliferation promoting agent", or simply a "proliferation promoting agent"), includes the protein GM-CSF, granulocyte colony stimulating factor (G-CSF), GRO-β, Flt-3 ligands, glutathione S-transferase inhibitors, angiotensin or analogs thereof, CD26 inhibitors, VLA4 inhibitors, kit ligands, vascular endothelial growth factor (VEGF), Steel factor (SLF, also known as Stem cell factor (SCF)), HGF, hepatocyte growth factor (scatter factor), Angiopoietin- 1, Angiopoietin-2, M-CSF, colony stimulating factor (CSF), acidic fibroblast growth factor (aFGF), and basic fibroblast growth factor (bFGF).

In embodiments in which the methods ofthe invention employ use of GM- CSF (also referred to as "granulocyte-macrophage colony stimulating factor"), it will be appreciated that the natural or recombinantly prepared protein having substantial identity to an amino acid sequence of human GM-CSF will be referred to. See published international application WO 86/00639, which is incorporated herein by reference. Recombinant human GM-CSF is hereinafter also referred to as "hGM- CSF".

See also Kim, CH. and Broxmeyer, H.E. (1998) Blood, 91: 100; Turner, M.L. and Sweetenham, J.W., Br. J. Haematol. (1996) 94: 592; Aiuuti, A. et al. (1997) J. Exp. Med. 185: 111; Bleul, C. et al. (1996) J. Exp. Med. 184: 1101; Sudo, Y. et al. (1997) Blood, 89: 3166; as well as references disclosed therein (disclosing additionally suitable EPC proliferation promoting agents).

In another embodiment ofthe invention, a CXCR4 antagonist may be administered in conjunction with a therapeutically effective amount of an inhibitor of vascular endothelial growth factor-mediated vascular permeability, for example, an inhibitor of a src-family kinase.

The natural or recombinantly prepared proteins, and their functional equivalents used in the method ofthe invention are preferably purified and substantially cell-free, which may be accomplished by known procedures.

Additional protein and nucleic sequences relating to the factors disclosed herein including SDF-1 can be obtained through the National Center for Biotechnology Information (NCBI)- Genetic Sequence Data Bank (Genbank). In particular, sequence listings can be obtained from Genbank at the National Library of Medicine, 38A, 8N05, Rockville Pike, Bethesda, MD 20894. Genbank is also available on the internet through the website ofthe National Center for Biotechnology Information. See generally Benson, D.A. et al. (1997) Nucl. Acids. Res. 25:1 for a description of Genbank. Protein and nucleic sequences not specifically referenced can be found in Genbank or other sources disclosed herein.

In accord with the methods of this invention, a CXCR4 antagonist can be administered to a mammal and particularly a human patient in need of such treatment. As an illustration, CXCR4 antagonist as well as therapeutic compositions including same are preferably administered parenterally. More specific examples of parenteral administration include subcutaneous, intravenous, infra-arterial, intramuscular, and intraperitoneal, with subcutaneous being preferred. In some embodiments, a CXCR4 antagonist is used to augment the effects of locally administered agents for neovascularization.

In embodiments of this invention in which parenteral administration is selected, the CXCR4 antagonist will generally be formulated in a unit dosage injectable form (solution, suspension, emulsion), preferably in a pharmaceutically acceptable carrier medium that is inherently non-toxic and non-therapeutic. Examples of such vehicles include without limitation saline, Ringer's solution, dextrose solution, mannitol and normal serum albumin. Neutral buffered saline or saline mixed with serum albumin are exemplary appropriate vehicles. Non-aqueous vehicles such as fixed oils and ethyl oleate may also be used. Additional additives include substances to enhance isotonicity and chemical stability, e.g., buffers, preservatives and surfactants, such as Polysorbate 80. The preparation of parenterally acceptable protein solutions of proper pH, isotonicity, stability, etc., is within the skill ofthe art.

Preferably, the product is formulated by known procedures as a lyophilizate using appropriate excipient solutions (e.g., sucrose) as a diluent.

Suitable dosage ranges for the compounds of formula (1) vary according to these considerations, but in general, the compounds are administered in the range of about 0.1 μg/kg-5 mg/kg of body weight; preferably the range is about 1 μg/kg-300 μg/kg of body weight; more preferably about 10 μg/kg-100 μg/kg of body weight. For a typical 70-kg human subject, thus, the dosage range is from about 0.7 μg-350 mg; preferably about 700 μg-21 mg; most preferably about 700 μg-7 mg. Dosages may be higher when the compounds are administered orally or transdermally as compared to, for example, i.v. administration.

Typical in vivo dosages for polypeptides such as SDF-1 will be guided by intended use however between from about 1 μg/kg/day to about lOOμg/kg/day will often be useful. Use of more specific dosages will be guided by parameters well known to those in this field such as the specific condition to be treated and the general health ofthe subject. See also U.S. Patent No. 5,578,301 for additional methods of administering GM-CSF.

It will be understood that the term "co-administration" is meant to describe preferred administration of at least two compounds or agents disclosed herein to the mammal, i.e., administration of one compound or agent in conjunction with, subsequent to, or prior to administration ofthe other compound or agent. It will be further understood that the term "in conjunction with" does not require administration of the compounds or agents in the same composition, or even at approximately the same time.

In embodiments in which co-administration of a DNA encoding a protein, e.g., an encoded EPC proliferation promoting protein, is desired, the nucleic acid encoding same can be administered to a blood vessel perfusing the ischemic tissue via a catheter, for example, a hydrogel catheter, as described by U.S. Patent No 5,652,225, the disclosure of which is herein incorporated by reference. The nucleic acid also can be delivered by injection directly into the ischemic tissue using the method described in PCT WO 97/14307.

The nucleotide sequence of numerous EPC proliferation promoting proteins, are readily available through a number of computer databases, for example, GenBank, EMBL and Swiss-Prot. Using this information, a DNA segment encoding the desired may be chemically synthesized or, alternatively, such a DNA segment may be obtained using routine procedures in the art, e.g, PCR amplification.

The term "therapeutically effective amount" refers to a sufficient amount of a compound, e.g., a small molecule, protein or nucleic acid delivered to produce an adequate therapeutic response in a subject, e.g., levels capable of inducing EPC mobilization into the peripheral blood circulation, as determined by standard assays disclosed throughout this application.

As used herein, "treatment" of a subject includes the application or administration of a therapeutic agent to a subject, e.g., a subject suffering from tissue ischemia (e.g., from a mycardial infarction), with the purpose of curing, healing, alleviating, relieving, altering, remedying, ameliorating, improving, or affecting the ischemia and/or the damage to the tissue resulting from the ischemia. It will be understood by those of skill in the art that a "method of treatment" does not require a complete "cure", or a complete absence of symptoms resulting from the ischemic event. A "method of treatment" refers to any method wherein the performance ofthe method leads to a beneficial effect in the subject on whom the method is performed.

By the term " standard EPC culture assay" or related term is meant an assay that includes at least one of and preferably all ofthe following steps. a) isolating mononuclear cells from about 0.5 ml peripheral blood ofthe mammal, b) culturing the cells in a suitable dish or plate in medium for several days and usually for about 4 days, at 37°C, c) staining the cells with acLDL-Dil and BS-1 lectin, and d) quantitating double positive cells as being indicative of EPCs.

More specific disclosure relating to the standard EPC culture assay can be found in the discussion and Examples that follow.

Reference herein to a "standard hind limb ischemia assay" or related term is meant to denote a conventional assay for inducing hind limb ischemia in accepted animal models and particularly the mouse or rabbit. Disclosure relating to conducting the assay can be found in Couffinhal, T. et al. (1998) Am. J. Pathol, infra; and Takeshita, S. et al. (1994) J. Clinical. Invest. 93: 662.

The present invention is further illustrated by the following examples. These examples are provided to aid in the understanding ofthe invention and are not construed as a limitation thereof. The contents of all references, patents and published patent applications cited throughout this application, as well as the figures, are incorporated herein in their entirety by this reference.

Example 1 - Cultured EPC Assay

Animals used in this study were handled in accordance with the guidelines ofthe Animal Care and Use Committee at St. Elizabeth's Medical Center of Boston. AMD3100 (125μg in lOOμl of saline) was administered to eight-week old male FVB/N mice (Jackson Lab, Bar Harbor, ME) by subcutaneous single injection. Control mice received lOOμl of saline by a similar procedure. Both groups of mice were sacrificed, and peripheral blood was harvested from subgroups of mice at 1, 3, 12 and 24 hours after injection. At each time point, blood was obtained from the heart immediately before sacrifice and separated by density gradient centrifugation with a Histopaque-1083 (Sigma). Light-density mononuclear cells were harvested and washed twice with Dulbecco's phosphate-buffered saline to which 5mM EDTA had been added. Contaminated red blood cells were hemolyzed using ammonium chloride solution (Stem Cell Technologies). Peripheral blood mononuclear cells (PBMNCs) were isolated from 500μl of peripheral blood obtained from each mouse. PBMNCs were cultured in EBM media (Clonetics, San Diego, CA) with 5% fetal bovine serum (FBS), antibiotics, and growth factors (EPC medium) on four-well glass slides coated with rat plasma vitronectin (Sigma) in 0.5% gelatin solution. Four days after culture, EPCs, recognized as attaching spindle-shaped cells, were assayed by co-staining with acetylated LDL (acLDL)-DiI (Biomedical Technologies, Stoughton, MA) and Bandeiraea simplicifolia (BS-1) lectin I (Vector Laboratories, Burlingame, CA), indicators of endothelial lineage, and conjugated with FITC (Sigma). EPCs were identified as double-positive cells under fluorescent microscopy. The number of double-positive cells per sample, measured in fifteen fields under 20x magnification, was counted in a blinded manner. More specific details ofthe cultured EPC assay can be found in Takahashi, T. et al. (1999) Nat. Genet. 5:434-438, incorporated herein by reference.

Example 2 - Change of MΝC and EPC Numbers By 24 Hours After a Single Injection of AMD-3100.

Mice were injected as described in Example 1. As shown in Figure 1, the numbers of both MNCs and EPCs rapidly increased after AMD-3100 injection, resulting in maximal MNCs and EPCs 1 hour after drug administration (613±89 cells/mm² for AMD-3100 vs. 292+30 for control, PO.01) . The number of EPCs, identified by acLDL uptake and BS-1 lectin reactivity, increased at one hour after injection and returned to baseline within 24 hours after injection. These values returned to baseline within 24 hours (n = 5 experiments).

Example 3 - Functional Study of AMD-3100 Injection After Myocardial Infarction.

Eight- week old male FVB mice were anesthetized with sodium pentobarbital (50 mg/kg IP). The animals were intubated orally with a 22G IV catheter and artificially ventilated with a respirator (Harvard Apparatus). A left intercostal thoracotomy was performed and the ribs were retracted with 5-0 polypropylene sutures. After the pericardium was opened, the left anterior descending (LAD) branch ofthe left coronary artery was ligated proximal to the bifurcation between the LAD and the diagonal branch using 8-0 polypropylene sutures and visualized with a dissecting microscope. Positive end-expiratory pressure was applied to fully inflate the lungs, and the chest was closed with 7-0 polypropylene sutures. After the closure of chest wall, mice randomly received either a single subcutaneous injection of 125μg AMD3100 (AMD group) or saline (control group). After physiological assessment at one, two and four weeks after MI, a subgroup ofthe mice were euthanized by intravenous administration of a lethal dose of pentobarbital. Transthoracic echocardiography (SONOS 5500, Hewlett Packard) was performed just before MI and one, two and four weeks after MI. Left ventricular diastolic (LVDd) and systolic (LVDs) dimensions and fractional shortening were measured at the mid-papillary muscle level. Hemodynamic measurements were obtained at two and four weeks after MI using a 1.0-French high-fidelity pressure catheter (Millar Instruments, Houston, TX) via the left carotid artery. LV systolic pressure and maximal positive (+dP/dt) and negative (-dP/dt) pressure development were recorded after stabilization of LV function and heart rate.

Example 4 - AMD-3100 Reduces Left Ventricle Dilation and Improves Left Ventricle Systolic Function Two Weeks After AMI.

Figures 2A-2B shows the results of an echocardiographic study performed one and two weeks after AMI. Left ventricular systolic (2.5±0.1 mm for AMD-3100 vs. 3.2+0.1 mm for control) and diastolic (3.8+0.1 mm for AMD-3100 vs 4.3±0.1 mm for control) dimensions and fractional shortening (34+1 % for AMD-3100 vs. 25±2% for control) in the AMD-3100 group were preserved two weeks after AMI, as compared to control (PO.01).

Example 5 - AMD-3100 Preserves Left Ventricle Function Two Weeks After AMI.

Figures 3A-3C show the results of hemodynamic measurements taken using a Millar catheter. Left ventricle (LV) systolic (71+2 mm Hg for AMD-3100 vs. 62±6 mm Hg for control) and end-diastolic (1.6+0.4 mm Hg for AMD-3100 vs. 5.3+1.8 mm Hg for control) pressures in the AMD-3100 group two weeks after AMI were improved, as compared to control (PO.05). LV +dP/dt and -dP/dt, as an indicator of LV function, two weeks after AMI in the AMD-3100 group were also higher than control (+dP/dt: 3383+104 mm Hg/s for AMD-3100 vs 2354±255 mm Hg/s for control; -dP/dt: 2213+113 mm Hg/s for AMD-3100 vs. 1750+196 mm Hg/s for control, PO.05). Further data were obtained as follows. Hemodynamic parameters obtained from echocardiography and a Millar catheter from wild-type mice who received AMD3100 or saline are also summarized in Table 1. LVDd, LVDs, fractional shortening, and heart rate before MI and one week after MI were not significantly different between the groups.

Beginning at two weeks post-MI, echocardiography revealed decreased ventricular remodeling in the AMD3100-treated mice. LVDd (2wks: 3.8+0.1 versus 4.3±0.1mm, 4wks: 4.0+0.1 versus 4.5±0.1mm, P<0.01) and LVDs (3wks: 2.5+0.2 versus 3.0±0.2mm, 4wks: 2.6+0.2 versus 3.2±0.2mm, P<0.01). [Consider moving this to a table.] Fractional shortening at two and four weeks after MI was also significantly higher in the AMD group, compared with the control group (2wks: 34+1 versus 25+ 1%; PO.01, 4wks: 28+1 versus 22+1%, PO.05). There was no significant difference in heart rate between the two groups. Hemodynamic measurements taken at two and four weeks after MI are shown in Table 1. Although there was no significant difference in left ventricular systolic pressure (LNSP) between the groups at two weeks after MI, left ventricular end- diastolic pressure (LNEDP) in the AMD group was significantly lower than in the control group (1.5+0.2 versus 3.4+OJ mmHg, PO.05). Moreover, four weeks after MI, LNEDP in the AMD group was also lower than in the control group (1.6+0.4 versus 5.3+1.8 mmHg, PO.05). Nevertheless, LVSP in the AMD group was higher than in the control group (71+2 versus 62+2 mmHg, P .05). LN +dP/dt at two and four weeks after MI was significantly preserved in the AMD group compared with the control group (2wks: 3475+168 versus 2550+242 mmHg/s, PO.05, 4wks: 3383+104 versus 2353+255 mmHg/s, PO.01).

Example 6 - AMD-3100 Improves Survival Rate After AMI.

Survival rates of mice treated with AMD-3100 or saline (control) after AMI are shown in Figure 4 A. 64% of mice treated with AMD-3100 were still living 14 weeks after AMI, as compared to 38 % of control mice (PO.05). In another group of mice, ten mice (42%) died in the AMD group, whereas 19 mice (70%) died in the control group. The survival rate four weeks after MI was higher in mice receiving AMD3100 than in mice receiving saline (PO.05, Figure 4B). Example 7 - Increased Capillary Density in the Border Zone at One and Two

Weeks After AMI.

The explanted hearts of sacrificed mice were sliced in a bread-loaf fashion into transverse sections from apex to base (base-, mid-, and apex-portions) and fixed with 4% paraformaldehyde. Tissues were embedded in paraffin and sectioned for elastic tissue/trichrome staining and immunohistochemistry using the murine-specific EC marker Bandeiraea simplicifolia lectin I (Isolectin B4) (Vector laboratories). Capillary density was assessed by histological examination of five randomly selected fields of tissue sections from segments ofthe left ventricular myocardium served by the occluded LAD. Capillaries were recognized as tubular structures positive for isolectin B4. Elastic tissue/trichrome-stained tissues from the mice four weeks after MI were used to measure the average ratio ofthe external circumference of fibrosis area to LV area. Immunohistochemistry of border zone sections using an antibody to isolectin B4 showed increased capillary density in the sections from AMD-3100-treated mice. Representative sections are shown in Figures 5A-5D. The increase (at two weeks, 4005+189/mm² for AMD-3100 vs. 2234+62/mm², PO.01) is quantitated in Figures 6A-6C. Elastic trichrome-stained tissue in the control group four weeks after MI indicated marked dilatations ofthe LV cavity consistent with the echocardiographic measurements.

Example 8 - AMD-3100 Decreases Percent Fibrosis Area Two Weeks After AMI.

AMD-3100-treated and control mice were sacrificed two weeks after AMI. Sections ofthe left ventricles (Figures 7A-7B) showed a statistically significant decrease (PO.05) in fibrosis area in the AMD-3100-treated mice (25+6% for AMD- 3100 vs. 46+4% for control). This decrease is quantitated in Figure 7C. Example 9 - AMD-3100 Enhances the Number of EPCs in Peripheral Blood One and Two Weeks After AMI.

To evaluate the effect of AMD-3100 on circulating EPC kinetics, EPC counts (cells/mm ) were taken from peripheral blood one and two weeks after AMI. At each time point after the induction of MI, mononuclear cells were isolated from peripheral blood and total BM cells that had been obtained by flushing the tibias and femurs. EPCs were counted by culturing as described in Example 1, and stained with both acLDL-Dil and BS-1 lectin. Double positive cells were counted in 15 fields under objective 20X magnification per sample in a blinded manner. AMD-3100-treated mice showed a statistically significant increase in the number of EPCs in the peripheral blood at both one (868+210/mm² for AMD-3100 vs. 485+33 mm² for control) and two weeks (556+47/mm² for AMD-3100 vs. 330±58/mm² for confrol) after AMI (PO.05). The results are shown in Figure 8. The number of cultured EPCs returned to basline at four weeks after AMI in both groups. Fluorescence-activated cell sorting (FACS) was used to identify EPCs from mononuclear cells isolated both from peripheral blood and bone marrow. The viable mononuclear cell population was analyzed for the expression of Sca-1 -FITC (Pharmingen) and Flk-1 (Santa Cruz) conjugated with the corresponding phycoerythrin-labeled secondary antibody (Sigma). Isotype-identical antibodies served as negative controls. Immunofluorescence-labeled cells were fixed with 2% paraformaldehyde and analyzed by quantitative flow cytometry using a FACStar flow cytometer (Becton Dickinson) and Cell Quest Software that counted 10,000 events per sample. Representative FACS analysis at one and four weeks after MI revealed a significant increase of EPCs in the AMD3100 group one week after MI, compared with the control group (11.3+1.4 versus 6J+1.1 %, P .05) (Figures 14A and 14C). To examine the effect of AMD3100 on the kinetics of bone marrow EPCs after MI, BM mononuclear cells were isolated from total BM cells obtained by flushing the tibias and femurs. FACS analysis was used to identify Sca-l/Flk-1 positive cells as EPCs. Representative FACS analysis at one and four weeks after MI is shown in Figure 15 A. AMD3100 prevented a significant decrease of EPCs in the AMD group one week after MI, compared with the control group (1.9+0.1 versus 1.6+0.1 %, PO.05) (Figure 15B) To clarify the mechanism of BM-EPC kinetics induced by AMD3100, RT- PCR was performed for MMP-9 mRNA expression on BM-mononuclear cells one week after MI was performed. RNA was extracted from mononuclear cells isolated from bone marrow using TRIzol reagent (Invitrogen) according to the manufacture's instruction. Reverse transcriptase-polymerase chain reaction (RT-PCR) ofthe MMP- 9 and GAPDH genes was performed using 1 μg of total RNA. PCR was performed for 25 cycles for both MMP-9 and GAPDH; each cycle maintained 94°C for 30 seconds and 64° C for three minutes. Amplification was carried out in 20- μl reaction mixtures containing 0.4 U Taq polymerase. MMP-9 expression was disrupted by deleting of most of exon 2 ofthe MMP-9 gene in the 129/SvEv genetic background (Jackson), as described previously. [Vu, 1998 #2370] Male eight-week-old MMP^"7' mice randomly received either 125μg AMD3100 or saline immediately after the induction of MI. Mononuclear cells from peripheral blood and total BM cells were isolated one week after MI and were examined by FACS analysis as described above. RT-PCR detected enhanced expression of MMP-9 but not MMP-2 in BM- mononuclear cells (Figure 15C). These data were strongly supported by FACS analysis for BM-mononuclear cells from MMP^"7" mice. Representative FACS analysis for quantification of Sca-l/Flk-1 positive cells is shown in Figurel5D. There was no significant difference between mice receiving AMD3100 and those receiving saline (Figure 15E).

Example 10 - Experimental Design - Tie2-LacZ/BMT Model

This Example describes the experimental design ofthe Tie2-LacZ/BMT mouse model. These mice express LacZ in bone marrow-derived cells that express the endothelial cell specific marker Tie-2 (see Takahashi, T. et al. (1999) Nat. Genet. 5:434-438). FVB/N background mice (n = 30) were irradiated to kill their endogenous bone marrow. They were then given a bone marrow transplant (BMT) of 2xl0⁶ mononuclear cells (MNCs) derived from age-matched (4 weeks old) Tie2-LacZ mice (FVB/N-TgN[TIE2LacZ]182Sato, Jackson Lab). AMIs were induced in the mice (now called Tie2-LacZ/BMT mice) by LAD ligation four weeks after BMT, by which time the bone marrow ofthe recipient mice had been reconstituted. Right after AMI, the mice were each given a single subcutaneous injection of AMD-3100 (125 μg) or saline (control). Bone marrow cells were obtained using procedures described above. Bone marrow mononuclear cells were also isolated by density centrifugation. Tissue analysis was done at one or two weeks.

Example 11 - AMD-3100 Augments Recruitment of Bone Marrow Derived EPCs One and Two Weeks After AMI.

Tie-2/LZ/BMT mice were sacrificed at one and two weeks after MI. The explanted hearts were sliced in a bread-loaf fashion into fransverse sections from apex to base (base-, mid-, and apex-portions). Mid-portions ofthe hearts were fixed in 4% paraformaldehyde for three hours at room temperature and incubated in X-gal solution overnight at 37°C. The target tissue samples were then placed in PBS [need to spell this out] and examined under a dissecting microscope for macroscopic identification of lacZ-expressing cells.Histological sections ofthe mid-portion heart tissue were counterstained with hematoxylin and eosin and assessed by light microscopy. The number of X-gal positive cells in six randomly chosen fields at 40x magnification were counted in a blinded manner. Apex-sections from the Tie-2/LZ/BMT mice were embedded in OCT compound (Miles Scientific) and snap-frozen in liquid nitrogen for fluorescence microscopy immediately after sacrifice. Immunohistochemical staining was performed using antibodies against the rabbit anti-β-galactosidase IgG (CORTEX Biochem) and the murine-specific EC marker fluorescein griffonia simplicifoha lectin I (Vector Laboratories).

Left ventricle sections of AMD-3100-treated and control Tie2-LacZ/BMT mice were analyzed one and two weeks after AMI. Macroscopically, there was marked increase in X-gal staining ofthe left ventricle in the AMD-3100 group at one and two weeks, as compared to the controls (Figures 9A-9D). This indicates that there is an increase in the recruitment of bone marrow derived EPCs in the left ventricle after AMI in the treated group. Dilation ofthe left ventricle and the thickness of antero-lateral wall were similar between the two groups. Microscopic (400X) counterstaining showed similar results (Figures 10A-10D). A quantitative analysis of the number of X-gal positive cells is shown in Figures 11 A-l IB. The quantitative analysis of X-gal positive cells was evaluated by histological examination of six randomly selected fields in the infarct and border area. There is a statistically significant increase in the number of X-gal positive cells in the AMD-3100 treated cells, as compared to the controls, at both 1 and 2 weeks after AMI (1 week: 3776+113/mm2 for AMD-3100 vs. 2231+323/mm2 for control; 2 weeks: 1906+138/mm2 for AMD-3100 vs. 1441±56/mm2 for control; PO.05).

Example 12 - Fluorescence Microscopy on Myocardium One Week After AMI.

Sections of ischemic (Figures 12A-12F) and intact (Figures 13A-13F) myocardium were stained for both BS lectin 1 (green fluorescence) and β- galactosidase (red fluorescence). Merged fluorescence microscopy (400X) showed a marked increase in double-positive cells in tissue taken from AMD-3100-treated mice. In a representative section, the AMD-3100-treated mice had eight double- positive cells, as compared to one double-positive cell in the control section. In another representative section, the AMD-3100-treated mice had eight double-positive cells, as compared to two double-positive cells in the control section.

Example 13 - Statistical Analysis All values were expressed as mean ± the standard error ofthe mean. Statistical significance was evaluated using Wilcoxon Rank Sum Test for comparisons between mice receiving AMD3100 and those receiving saline. Overall survival of all the mice was assessed by Kaplan-Meier analysis. Survival in individual experimental groups was also analyzed by Fisher's extract probability test. A p value of less than 0.05 was considered statistically significant. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments ofthe invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

What is claimed:

1. A method of treating tissue ischemia comprising administering to a subject a therapeutically effective amount of a CXCR4 antagonist, wherein the CXCR antagonist elevates the peripheral blood endothelial progenitor cell (EPC) count ofthe subject, thereby treating the tissue ischemia in the subject.

2. The method of claim 1, further comprising administering a therapeutically effective amount of an agent that promotes EPC proliferation to the subject.

3. The method of claim 2, wherein the agent that promotes EPC proliferation is administered to the subject prior to the admimsfration ofthe CXCR4 antagonist.

4. The method of claim 2, wherein the agent that promotes EPC proliferation is SDF-1.

5. The method of claim 2, wherein the agent that promotes EPC proliferation is selected from the group consisting of GRO-β, a Flt-3 ligand, a glutathione S-transferase inhibitor, angiotensin or an analog thereof, a CD26 inhibitor, a VLA4 inhibitor, and a kit ligand.

6. The method of any of claims 1 -5, further comprising administering a therapeutically effective amount of an inhibitor of vascular endothelial growth factor- mediated vascular permeability to the subject.

7. The method of any of claims 1-6, further comprising: a) removing EPCs from the subject, b) contacting the EPCs with a therapeutically effective amount of an agent that promotes EPC proliferation, and c) returning the EPCs to the subject.

8. The method of any of claims 1 -7 , wherein the subj ect has had or is having an acute myocardial infarction.

9. The method of claim 8, wherein the CXCR4 antagonist is administered to the subject less about 12 hours or less after suffering from an acute myocardial infarction.

10. The method of any of claims 1-9, wherein the subj ect is suffering from or at risk for developing restenosis.

11. The method of any of claims 1-10, wherein the subj ect has suffered or is suffering from a disorder or condition selected from the group consisting of arteriosclerosis, stroke, chronic ischemia of myocardium, chronic ischemia of lower extremities, and organ regeneration in mycoardium, limbs, brain, or liver.

12. The method of any of claims 1-11, wherein the CXCR4 antagonist is administered to the subject by an intravenous or subcutaneous route.

13. The method of any of claims 1-12, wherein the CXCR4 antagonist is administered to the subject in the dosage range of about 0.1 μg/kg - 5 mg/kg of body weight.

14. The method of any of claims 1-13, wherein the CXCR4 antagonist is administered to the subject in a single dose or by continuous infusion.

15. The method of any of claims 1-14, wherein the CXCR4 antagonist has the formula:

Z-linker-Z'

or a pharmaceutically acceptable salt thereof wherein Z is a cyclic polyamine containing 9-32 ring members of which 3-8 are nitrogen atoms, said nitrogen atoms separated from each other by at least 2 carbon atoms, and wherein said heterocycle may optionally contain additional heteroatoms besides nitrogen and/or may be fused to an additional ring system; wherein Z' may be embodied in a form as defined by Z above, or alternatively may be ofthe formula

— N(R)— (CR₂) — X (l) wherein each R is independently H or straight, branched or cyclic alkyl (1- 6C), n is 1 or 2, and X is an aromatic ring, including heteroaromatic rings, or is a mercaptan; and wherin "linker" represents a bond, alkylene (1-6C) or may comprise aryl, fused aryl, oxygen atoms contained in an alkylene chain, or may contain keto groups or nitrogen or sulfur atoms.

16. The method of claim 15, wherein Z and Z' are both cyclic polyamines.

17. The method of any of claims 15-16, wherein Z and Z' are identical.

18. The method of any of claims 15-16, wherein Z contains 12-24 members and contains 4 nitrogen atoms.

19. The method of any of claims 15-18, wherein Z and Z' are both 1,4,8,11 -tetraazocyclotetradecane.

20. The method of any of claims 15-19, wherein the linker comprises an aromatic ring bracketed by two methylene moieties.

21. The method of any of claims 15-20, wherein the linker is 1 ,4- phenylene-bis-methylene.

22. The method of any of claims 1-21, wherein the CXCR4 antagonist is 1 , 1' - 1 ,4-phenylene-bis-(methylene)-bis- 1 ,4,8 , 11 -tetraazacyclotefradecane (AMD- 3100).

23. The method of claim 15, wherein the CXCR4 antagonist is selected from the group consisting of:

N-[l,4,8,ll-tetraazacyclotetradecanyl-l,4-phenylenebis(methylene)]-2- aminomethyl)ρyridine;

7,7 ' -[ 1 ,4-phenylenebis(methylene)]bis-4,7, 10, 17-tetraazabicyclo-[ 13.3. 1 ]heptadeca- l(17),13,15-triene; 7,7' -[ 1 ,4-phenylenebis(methylene)]bis-3 ,1,11,17-tetraazabicyclo[ 13.3. ljheptadeca- l(17),13,15-triene;

l,r-[l,3-phenylenebis(methylene)]-bis-l,4,8,ll-tefra-azacyclotetradecane;

l,r-[l,4-phenylenebis(methylene)]-bis-l,4,8,l l-tetra-azacyclotetradecane;

1 , 1 '-[ 1 ,4-phenylene-bis-(methylene)] -bis- 1 ,4,7,10-tetraazacyclotetradecane;

1 , 1 ' -[1 ,3 -phenylene-bis-(methylene)]-bis- 1,4,1,10-tetraazacyclotetradecane;

11,11 '-(l,2-propanediyl)bis-l,4,8,l 1-tetraazacyclotetradecane;

N-[4-(l,4J-triazacyclotetra-decane)-l,4-phenylenebis(methylene)]-2- (aminomethyl)pyridine;

N-[7-(4,7, 10-triazabicyclo[ 13.3. 1 ]heptadeca-l (17), 13,15-triene)-l ,4- phenylenebis(methylene)]-2-(aminomethyl)pyridine;

N-[7-(4,7,10,17-tetraazabicyclo[13.3. l]heptadeca-l(17),13,15-triene)-l,4- phenylenebis(methylene)] -2-(aminomethyl)pyridine; and

N-[4-[4,7,10,17-tetraazabicyclo[13.3. l]heptadeca-l(17),13,15-triene]-l,4- phenylenebis(methylene)]-2-(ammomethyl)pyridine.

24. The method of any of claims 15-23, wherein formula (1) is in the form of a pharmaceutically acceptable salt.

25. The method of claim 24, wherein the pharmaceutically acceptable salt is an acid addition salt.