Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
  • A61L27/38—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells
  • A61L27/3839—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells characterised by the site of application in the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/24—Collagen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
  • A61L27/38—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix containing added animal cells
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/40—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
  • A61L27/44—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having a macromolecular matrix
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L27/54—Biologically active materials, e.g. therapeutic substances
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
  • A61P17/02—Drugs for dermatological disorders for treating wounds, ulcers, burns, scars, keloids, or the like
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
  • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
  • C07K14/575—Hormones
  • C07K14/61—Growth hormone [GH], i.e. somatotropin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2310/00—Prostheses classified in A61F2/28 or A61F2/30 - A61F2/44 being constructed from or coated with a particular material
  • A61F2310/00005—The prosthesis being constructed from a particular material
  • A61F2310/00365—Proteins; Polypeptides; Degradation products thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
  • A61L2300/412—Tissue-regenerating or healing or proliferative agents
  • A61L2300/414—Growth factors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
  • A61L2300/426—Immunomodulating agents, i.e. cytokines, interleukins, interferons
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
  • A61L2300/428—Vitamins, e.g. tocopherol, riboflavin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/60—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a special physical form
  • A61L2300/64—Animal cells

Definitions

• the field of the invention is medical devices used in vivo or in vitro for production and delivery of medically useful substances.
• the means used to deliver medically useful substances can significantly affect their efficacy.
• the standard route of administration for many such substances is either oral, intravenous, or subcutaneous.
• Each has inherent limitations which can affect the therapeutic utility of the substances being delivered.
• many protein-based drugs have short half-lives and low bioavailabilities, factors that must be considered in their formulation and delivery.
• various devices have been developed to deliver medically useful substances, including portable pumps and catheters, there is still a significant need for improved delivery devices.
• Many medically useful substances, including proteins, glycoproteins, and some peptide and nonpeptide hormones are more efficiently produced by cultured cell ⁇ than via artificial synthetic routes.
• Appropriate cells are typically cultured in bioreactors, and the desired product purified therefrom for administration to the patient by standard means, e.g. orally or by intravenous or subcutaneous injection.
• the cells may be implanted directly into the patient, where they produce and deliver the desired product. While this method has a number of theoretical advantages over injection of the product itself, including the possibility that normal cellular feedback mechanisms may be harnessed to allow the delivery of physiologically appropriate levels of the product, it introduces additional complexities.
• fibroblasts for example, exist naturally in a rich network of extracellular matrix composed primarily of collagen
• a implantation device consisting of a solid, unitary piece of collagen gel (a "collagen matrix") in which the cells are embedded (e.g., Bell, U.S. Patent No. 4,485,096).
• Other substances such as polytetrafluoro-ethylene (PTFE) fibers (Moullier et al., Nature Genetics, 4:154, 1993; WO 94/24298), may be included in the collagen implant to impart strength or other desirable characteristics to the collagen gel.
• PTFE polytetrafluoro-ethylene
• collagen matrices can be substantially improved by the addition of microspheres to the collagen matrix, thereby forming what is herein termed a "hybrid matrix". This may be accomplished by mixing microspheres with the cells and soluble collagen prior to gelling of the collagen to form the matrix. If desired, the microspheres and cells can be cultured together for a period which permits the cells to adhere to the microspheres before addition of the non- gelled collagen solution; alternatively, the three constituents can be mixed essentially simultaneously or in any desired order, followed by gelation of the soluble collagen within the mixture, to form a gelled mixture consisting of insoluble collagen fibrils, cells and microspheres.
• the invention thus includes an article or device having a body made of matrix material that includes insoluble collagen fibrils, and disposed within the body:
• vertebrate cells particularly mammalian cells such as cells derived from a human, chimpanzee, mouse, rat, hamster, guinea pig, rabbit, cow, horse, pig, goat, sheep, dog, or cat
• mammalian cells such as cells derived from a human, chimpanzee, mouse, rat, hamster, guinea pig, rabbit, cow, horse, pig, goat, sheep, dog, or cat
• a plurality of microspheres (or beads) each of which consists primarily of (i.e., greater than 50% of its dry weight is) one or more substances selected from a list including collagen (preferably type I collagen) , polystyrene, dextran, polyacrylamide, cellulose, calcium alginate, latex, polysulfone, and glass (e.g., glass coated with a gel such as collagen, to improve adherence of cells) .
• collagen preferably type I collagen
• polystyrene dextran
• polyacrylamide polyacrylamide
• cellulose calcium alginate
• latex latex
• polysulfone polysulfone
• glass e.g., glass coated with a gel such as collagen, to improve adherence of cells
• at least 70%, and preferably at least 80% (most preferably between approximately 90% and approximately 100%, e.g., at least 95%) of each microsphere's dry weight is one or more of the listed substances.
• microspheres which are described as consisting essentially of purified collagen include ICN Cellagen" 1 Beads and Cellex Biosciences macroporous microspheres.
• the microspheres are preferably of a porous consistency, but may be smooth, and typically have an approximately spherical shape with a diameter of approximately 0.1 to 2 mm (e.g., between approximately 0.3 and 1 mm).
• the shape and size of microspheres from any particular lot or preparation will vary within manufacturing tolerances.
• the article may be configured to be implanted into an animal, e.g., a mammal such as a human patient, or may be designed for producing cellular products in vitro ; e.g., in an extracorporeal bioreactor apparatus having a means for shunting blood from an animal to the article and then back into a blood vessel of the animal, or in a bioreactor or other vessel from which medium containing the desired cellular product can be recovered for purification and the preparation of a pharmaceutical agent.
• an animal e.g., a mammal such as a human patient
• the article may be configured to be implanted into an animal, e.g., a mammal such as a human patient, or may be designed for producing cellular products in vitro ; e.g., in an extracorporeal bioreactor apparatus having a means for shunting blood from an animal to the article and then back into a blood vessel of the animal, or in a bioreactor or other vessel from which medium containing the
• the cells may be derived from one or more cells removed from the patient, and preferably are transfected cells containing exogenous DNA encoding one or more medically useful polypeptides such as an enzyme, hormone, cytokine, colony stimulating factor, angiogenesis factor, vaccine antigen, antibody, clotting factor, regulatory protein, transcription factor, receptor, or structural protein.
• one or more medically useful polypeptides such as an enzyme, hormone, cytokine, colony stimulating factor, angiogenesis factor, vaccine antigen, antibody, clotting factor, regulatory protein, transcription factor, receptor, or structural protein.
• polypeptides examples include human growth hormone (hGH), Factor VIII, Factor IX, erythropoietin (EPO) , albumin, hemoglobin, alpha-1 antitrypsin, calcitonin, glucocerebrosidase, low density lipoprotein (LDL) receptor, IL-2 receptor, globins, immunoglobulins, catalytic antibodies, the interleukins, insulin, insulin-like growth factor 1 (IGF-1) , parathyroid hormone (PTH) , leptin, the interferons, nerve growth factors, basic fibroblast growth factor (bFGF) , acidic FGF (aFGF) , epidermal growth factor (EGF) , endothelial cell growth factor, platelet derived growth factor (PDGF) , transforming growth factors, endothelial cell stimulating angiogenesis factor (ESAF) , angiogenin, tissue plasminogen activator (t-PA) , granulocyte colony stimulating factor
• the exogenous DNA can be a regulatory sequence that will activate expression of an endogenous gene (for example, using homologous recombination as described in WO94/12650-PCT/US93/11704, which is incorporated by referenced herein) .
• any type of cell which is capable of attaching to collagen and/or the microspheres, and which exhibits a desirable property such as expression of a medically useful cellular product or performance of an essential structural or metabolic function, can be utilized in the matrices of the invention.
• Examples include adipocytes, astrocytes, cardiac muscle cells, chondrocytes, endothelial cells, epithelial cells, fibroblasts, gangliocytes, glandular cells, glial cells, hematopoietic cells, hepatocytes, keratinocytes, myoblasts, neural cells, osteoblasts, pancreatic beta cells, renal cells, smooth muscle cells and striated muscle cells, as well as precursors of any of the above.
• more than one type of cell can be included in a given matrix.
• the cells may be present as clonal or heterogenous populations.
• the collagen in the matrix material is preferably type I, but may be any other type of collagen.
• the matrix material may optionally include two or more types of collagen (e.g., selected from types I, II, III, IV, V, VI, VII, VIII, IX, X, and XI), as well as any additional components that impart desirable characteristics to the resulting matrix: e.g., agarose, alginate, fibronectin, laminin, hyaluronic acid, heparan sulfate, dermatan sulfate, chondroitin sulfate, sulfated proteoglycans, fibrin, elastin, or tenascin.
• any of the above mentioned collagenous and non-collagenous components may be derived from human sources or from another animal source.
• Such fibers can, for example, be made of a material that includes nylon, dacron, polytetrafluoro-ethylene, polyglycolic acid, polylactic/polyglycolic acid polymer mixtures, polystyrene, polyvinylchloride co-polymer, cat gut, cotton, linen, polyester, or silk.
• hybrid matrices can be prepared which contain at least approximately two (and preferably approximately three) times as many cells as matrices prepared with soluble collagen alone, assuming the number of cells inoculated and the initial production volume are equivalent.
• the total amount of polypeptide expressed by the cells embedded in a given hybrid matrix in a given time period is typically significantly higher (e.g. , at least 50% higher, preferably at least 100% higher, and more preferably at least 200% higher) than achieved with a standard collagen matrix of equivalent volume.
• the hybrid matrix of the invention is generally prepared by a process that includes the following steps: forming a mixture that includes (a) a plurality of vertebrate cells; (b) a plurality of microspheres, each of which consists primarily of one or more substances selected from the list consisting of collagen, polystyrene, dextran, polyacrylamide, cellulose, calcium alginate, latex, polysulfone, and glass; and (c) a solution comprising soluble collagen; causing the soluble collagen in the mixture to form a gel of insoluble collagen fibrils in which the cells and the microspheres are embedded; and exposing the gel to culture conditions which cause the gel to become smaller by the exclusion of liquid, thereby forming the body of the article.
• Gelation is typically triggered by raising the pH of the relatively acidic collagen solution to above 5, e.g., by addition of concentrated, buffered culture medium, whereupon the collagen forms insoluble fibrils.
• the gel will take the shape of the interior of the mold.
• the contraction of the gel is effected by the cells in the mixture, which attach to the fibrils and cause it to contract to a smaller version of the molded shape (e.g. , a disk, as in the case where the mold is a petri dish which is cylindrical in shape) .
• the matrix may be utilized immediately after manufacture, may be cultured to increase the number of cells present in the matrix or to improve their functioning, or may be cryopreserved indefinitely at a temperature below 0°C.
• a medically useful polypeptide such as one listed above, may be delivered to a patient by a treatment method that involves providing a hybrid matrix containing cells which secrete the polypeptide of interest, and implanting the article in the patient in a selected site, such as a subcutaneous, intraperitoneal, sub-renal capsular, inguinal, intramuscular or intrathecal site.
• the matrix may be implanted at the site of a preexisting wound.
• the cells may be derived from one or more cells removed from the patient, and are preferably transfected in vitro with exogenous DNA encoding the polypeptide.
• they may be cells which naturally secrete the polypeptide or perform the desired metabolic function (e.g., hepatocytes or pancreatic beta cells) .
• the medically useful polypeptide may be administered to the patient by shunting a portion of the patient's blood through the apparatus described above, so that the polypeptide secreted by the cells in the hybrid matrix mixes with the blood.
• any such apparatus known to those in that field can be adapted to accommodate the matrix of the invention.
• blood shunted into a device which contains a perm-selective membrane surrounding a matrix of the present invention will result in the delivery of a therapeutic product of the matrix to the blood.
• a device similar to an artificial pancreas may be used for this purpose.
• hybrid matrices of the invention is as a means for producing a polypeptide in vitro .
• This method includes the steps of placing the hybrid matrix under conditions whereby the cells in the matrix express and secrete the polypeptide; contacting the matrix with a liquid such that the cells secrete the polypeptide into the liquid; and obtaining the polypeptide from the liquid, e.g. , by standard purification techniques appropriate for the given polypeptide.
• the matrix is anchored to a surface and is bathed by the liquid; alternatively, the matrix floats freely in the liquid.
• Cells embedded in the hybrid matrix function at a high level in a small space.
• the first step in purification of the expressed polypeptide is considerably more efficient with the matrices than with most standard methods of cell culture.
• Fig. 1 is a map of hGH expression plasmid pXGH302.
• Fig. 2 is a plan view in partial section of one embodiment of the invention.
• Fig. 3 is a graph showing the in vivo hGH levels in nude mice implanted with either a collagen matrix or a hybrid collagen matrix containing HF165-24 cells, human skin fibroblasts stably transfected with pXGH302 and expressing hGH.
• EXAMPLE I This example describes the procedures utilized to prepare a clonal cell strain of human fibroblasts stably transfected with the plasmid pXGH302 secreting recombinant human growth hormone (hGH) , and to combine them with porous collagen microspheres in a hybrid matrix of the invention.
• Such matrices are referred to as hybrid collagen matrices (HCM) .
• Fibroblasts were isolated from freshly excised human foreskins by an enzymatic dissociation technique. Upon confluency, primary cultures were dislodged from the plastic surface by mild trypsinization, diluted and replated to produce the secondary cell culture for transfection. Plasmid pXGH302 was constructed as decribed in Example II, and transfection was carried out by eiectroporation, a process in which cells are suspended in a solution of plasmid DNA, placed between a pair of oppositely charged electrodes, and subjected to a brief electric pulse.
• Treated cells were selected in G418-containing medium for 10-14 days. Cells that integrated the plasmid into their genomes stably expressed the product of the neo gene and formed colonies resistant to killing by the neomycin analog G418. Each colony, consisting of a clonal population of cells, was individually removed from its position on the tissue culture dish by trypsinization. Those clones scoring positive for hGH expression were expanded for quantitative assays, and clone HF165-24 was chosen for futher use.
• Collagen microspheres (Cellex Biosciences cat. #YB00-0015UW) were transferred from each original bottle provided by the manufacturer ( ⁇ 10ml per bottle) into 50 ml conical tubes (1 tube per bottle) . The microspheres were allowed to settle in the tube, and the storage buffer solution was aspirated off. Microsphere wash medium (DMEM with 1% calf serum and 1% penicillin/streptomycin) was added to the 50 ml mark on the graduated tube, the microspheres allowed to settle, and the medium aspirated off. This series of washing steps was repeated for a total of 4 washes.
• DMEM 1% calf serum and 1% penicillin/streptomycin
• microspheres were transferred to a 250 ml Erlenmeyer flask using a 25 ml plastic pipette, limiting the volume of microspheres to 100 ml per 250 ml flask.
• Microsphere wash medium was added to the 250 ml mark, and the flask was capped and placed in a tissue culture incubator at 37 'C for 2-3 hours. The flask was removed from the incubator, the microspheres allowed to settle, and the wash medium aspirated off. This series of incubation and washing steps was repeated for a total of 3 washes.
• a mixture of equal volumes of modified 2x DMEM (2x DMEM with 9 g/L glucose, 4 mM L- glutamine, and 22.5 mM HEPES) and calf serum was prepared according to Table 1. (Note: for volumes greater than 250 ml, the total pooled volume should be divided into appropriately sized tubes.)
• the cell pellet was resuspended in the 2x DMEM-calf serum mixture.
• the collagen microspheres were mixed with the cell suspension by adding 1 - 2 ml of the cell suspension to the packed microspheres and then transferring the concentrated microspheres by 10 ml pipette into the remaining cell suspension, followed by gentle mixing with the pipette.
• the mixture was placed on ice and the appropriate volume of collagen solution was added (rat tail Type I collagen; UBI cat #08-115, diluted to concentration of 4.0 mg/ml in 0.02 M acetic acid), as indicated in Table 1.
• the contents of the tube were mixed carefully (avoiding creating bubbles or frothing) using a 10 ml glass pipette, until the matrix solution appeared homogenous.
• an appropriate volume of the collagen/cell/microsphere/medium mix was added to a sterile petri dish with a pipette (10 or 25 ml capacity) , according to the total volume per dish listed in Table 1.
• the mix was agitated by pipetting occasionally during the filling of dishes to prevent settling of cells or microspheres.
• the filled dishes were placed in a 37°C, 5% C0 , 98% relative humidity tissue culture incubator and left undisturbed for approximately 24 h, during which time the contents gelled and the size of the gel decreased in all dimensions to form the hybrid matrices of the invention, which were approximately 50% of the diameter and 10% of the volume of the non-gelled mixture.
• One embodiment of the hybrid matrix of the invention is illustrated in Fig. 2.
• the matrix 10 consists of a contracted collagen gel body 12 in which are embedded vertebrate cells 14 and microspheres 16. For clarity in this figure, the cells are shown as dots separate from the microspheres. In fact, most of the cells would be expected to be attached to the microspheres, and would be substantially smaller than represented in the figure.
• EXAMPLE II pXGH302 was constructed by subcloning the 6.9 kb Hindlll fragment extending from positions 11,960-18,869 in the human HPRT sequence (Edwards et al., Genojiiics, 6:593-608, 1990; Genbank entry HUMHPRTB) and including exons 2 and 3 of the HPRT gene, into the Hindlll site of pTZ18R (Pharmacia P-L Biochemicals, Inc.).
• the resulting clone was cleaved at the unique Xhol site in exon 3 of the HPRT gene fragment, and the 1.1 kb Sa_.I-X.noI fragment containing the neo gene from pMClNeo (Stratagene) was inserted, disrupting the coding sequence of exon 3.
• pE3neo One orientation, with the direction of neo transcription opposite that of HPRT, was chosen and designated pE3neo.
• pXGH5 Yielden et al., Mol. Cell. Biol.
• pXGH302 A map of plasmid pXGH302 is shown in Fig. 1. In this figure, the position and orientation of the hGH coding region and the mouse metallothionein-I promoter (mMT-I) controlling hGH expression are noted. The positions of basal promoter elements (TATA) , transcription initiation sites (CAP) , and translation initiation sites (ATG) are indicated.
• TATA basal promoter elements
• CAP transcription initiation sites
• ATG translation initiation sites
• neo gene transcription is controlled by the polyoma enhancer/herpes simplex virus (HSV) thymidine kinase (TK) gene promoter.
• HSV polyoma enhancer/herpes simplex virus
• TK thymidine kinase
• HPRT denotes the positions of sequences from the human hypoxanthine- guanine phosphoribosyl transferase locus.
• Plasmid pXGH302 utilizes the pTZ18R (Pharmacia P-L Biochemicals, Inc.) backbone, a derivative of plasmid pUC18 (Yanisch- Perron et al., Gene 33: 103-119, 1985) carrying a T7 RNA polymerase promoter and the fl origin of replication.
• EXAMPLE III This example illustrates a method of making a hybrid collagen matrix in which transfected cells prepared as described above are precultured with the microspheres prior to formation of the hybrid collagen matrix.
• Such "precultured" hybrid collagen matrices are referred to as PCHCM.
• Trypsinized transfected cells are seeded onto washed collagen microspheres at a ratio of 2 x IO 6 cells per ml microspheres (e.g. 10 x IO 6 cells onto 5 ml microspheres) by the following protocol:
• Total number of cells/ml microspheres 1000 mg/ (mg weight of sample) X (cell number in sample) X 0.5.
• the cell/microsphere mixture is transferred from the 125 ml Erlenmeyer flask to a 250 ml spinner flask (Bellco Microcarrier Spinner Flasks, 250 ml, with model #1965-60001 impeller shafts) , growth medium is added to the 150 ml gradation mark, and the spinner flask is placed on a magnetic stirrer plate (set at 50 rpm) in a tissue culture incubator. The culture is fed with fresh medium the next day and 3 times weekly thereafter by allowing the microspheres to settle on the bottom of the flask, aspirating "spent" medium to the 50 ml mark on the flask, and adding fresh growth medium to the 200 ml mark.
• a 250 ml spinner flask Bellco Microcarrier Spinner Flasks, 250 ml, with model #1965-60001 impeller shafts
• growth medium is added to the 150 ml gradation mark
• the spinner flask is placed on a
• PCHCM Preparation of Precultured Hybrid Collagen Matrices fPCHCM
• PCHCM are produced by the following protocol: l. When the desired density of cells per ml microspheres is achieved (as determined by cell counts) , remove microspheres containing cells from the spinner flask.
• microsphere/DMEM/calf serum mixture diluted to concentration of 4.0 mg/ml in 0.02M acetic acid
• the contents of the tube are mixed carefully (avoiding creating bubbles or frothing) using a 10 ml glass pipette, until matrix solution appears homogenous.
• Hybrid matrices are maintained in culture by feeding the matrices on day 1, and then 2 to 3 times weekly using the following protocol: 1. Carefully aspirate the culture medium.
• the medium may be supplemented with ascorbic acid 2-phosphate and/or TGF-,9 (e.g. 10-50 ⁇ g/ml ascorbic acid 2-phosphate and/or 1-10 ng/ml TGF- ⁇ ) .
• the diameter of a hybrid collagen matrix can be determined using the following procedure: 1. Place the petri dish containing the matrix to be measured on top of a metric ruler resting on a dark background. 2. Record diameters (in centimeters) as desired: e.g., daily for the first 2 weeks, every other day after the first 2 weeks, and on days of cell quantitation for the duration of the experiment.
• C. Cells can be recovered and quantified from a hybrid collagen matrix as follows:
• Cell Counting a. Measure the total volume of each digested cell suspension using the gradations on the side of the centrifuge tube. b. For measuring cell viability, remove 0.1 ml of cell suspension and add to 0.1 ml of 0.08% trypan blue in a 1.5 ml microcentrifuge tube. Mix by tapping the tube lightly. c. Count the viable and dead cells using a hemacytometer. If necessary, further dilute the cell suspension in PBS prior to adding the trypan blue. Calculate the total number of cells, taking into consideration the total volume measured in step 2a.
• This example describes experiments varying the inoculum density of clones of human fibroblasts stably transfected with the plasmid pXGH302 in a hybrid collagen matrix, to determine the cell density that can be supported in HCM. hGH production by each HCM was also monitored.
• Hybrid collagen matrices were produced with 3 inoculum densities (ID) of the stably transfected hGH- expressing neonatal foreskin fibroblast clone designated HF165-24. The densities were 5, 10, and 20 x 10 6 cells per HCM. For each ID, 9 HCM were produced in 60 mm dishes.
• the hybrid matrix production medium for each ID consisted of 9 ml of modified 2x DMEM, 9 ml of calf serum, 9 ml of collagen microspheres, and 9 ml of 4 mg/ml soluble rat tail collagen, in 50 ml conical tubes.
• HCM Growth Medium
• DMEM 10% calf serum, and 1% Pen/Strep
• HCMs were transferred on day 3 from 60 mm petri dishes to 100 mm petri dishes using flat forceps, and 10 ml of Growth Medium was added per dish.
• medium was aspirated from each HCM, matrices were rinsed with 5 ml of Hank's Balanced Salt Solution (HBSS) and aspirated, and 10 ml of Growth Medium was added to each dish.
• HBSS Hank's Balanced Salt Solution
• the time of Growth Medium addition to HCM was noted in order to take a 24 h medium sample the following day (day 7) .
• This rinse and feeding procedure was repeated on days 13 and 20 to provide day 14 and day 21 medium samples.
• the medium samples were assayed for hGH as indicated below.
• the HCM were also refed on days 10 and 17 without the rinse step.
• Example IV Digestion of 3 HCM per ID for cell counts occurred on days 7, 14, and 21 after medium samples were taken, as described in Example IV. Production of hGH by HCM at the indicated time points was measured by radioimmunoassay (Nichols Institute) of the 24 h medium samples, as described in Example XII below.
• CM collagen matrices
• HCM "Standard" collagen matrices
• CM were prepared by replacing the volume occupied by microspheres in HCM with additional soluble collagen, to give a ratio of 1 part 2x DMEM, 1 part calf serum, and 2 parts soluble collagen per CM.
• a direct comparison of CM with HCM was assessed as follows. The clone of human fibroblasts stably transfected with the plasmid pXGH302, designated HF165-24, was used. Nine matrices of each type, at each of two ID (1 x io 6 and 5 x 10° cells per matrix) , were produced.
• CM 9 x IO 6 cells (for 1 x 10° ID) and 45 x IO 6 cells (for 5 x 10° ID) were resuspended in 9 ml of 2x DMEM + 9 ml of calf serum in 50 ml tubes.
• CM a total of 18 ml of rat tail type I collagen solution (4 mg/ml) was added to each ID set, and matrices were formed as described above in Example I.
• HCM 9 ml collagen microspheres and 9 ml of rat tail type I collagen solution (4 mg/ml) were added to each ID set, and HCM were formed according to Example I.
• Matrices were kept in the original 60 mm dish and fed with a volume of 5 ml Growth Medium.
• Cell numbers per matrix, as well as hGH production per matrix, were determined on days 7, 14, and 30 as described for Example V.
• the maximum cell densities (measured on day 14) and hGH production achieved by the 2 types of matrices at the 2 densities are summarized in Table 4.
• Table 4 the hybrid type of matrix allowed for a higher density of cells and a substantially greater production of hGH per matrix, compared with the standard collagen matrix without microspheres.
• PCHCM precultured hybrid collagen matrices
• the microspheres were transferred from each Erlenmeyer flask into a 250 ml spinner flask, Growth Medium was added to the 150 ml mark of each spinner flask, and flasks were placed on a magnetic stirrer plate set at 50 rpm in a tissue culture incubator. The following day. Growth Medium was added up to the 200 ml mark of each spinner flask, and flasks were refed 3 times weekly by aspirating medium to the 50 ml mark and adding fresh medium up to 200 ml.
• the density of cells per ml microspheres was determined.
• a small sample of microspheres (-0.1 - 0.2 ml) was removed from each flask and placed in pre-weighed 5 ml polystyrene tubes. Excess medium was removed from each tube by aspiration, and the tube containing the microsphere sample was weighed.
• One ml of a 2 mg/ml collagenase type IA solution in PBS was added to each tube, and the tubes were covered with parafilm, and placed in a 37'C waterbath. At 15 minute intervals, the tubes containing microspheres were tapped lightly to disperse clumps.
• Total # of cells/ml microspheres 1000 g/ (mg weight of sample) x (cell# in sample) x
• the final number of cells per matrix was 9.6 x IO 6 , since each matrix was composed of 0.5 ml of microspheres containing 19.2 x IO 6 cells per ml.
• These precultured hybrid collagen matrices (PCHCM) were refed after 24 h by aspirating the medium and adding 5 ml of Growth Medium. The PCHCM were refed on days 4, 7, 11, 14, 18, and 20 with 6 ml of Growth Medium. On days 7, 14, and 20, the PCHCM were also rinsed with 4 ml of HBSS prior to addition of medium, and the time of medium addition was noted.
• PCHCM were dissociated into single cells by vigorous pipetting with a 5 ml glass pipette. Further dissociation was deemed necessary due to the presence of clumps, and a solution of lOx trypsin:EDTA (0.5% trypsin, 5.3 mM EDTA) was added to give a final trypsin concentration of IX in the collagenase. The tubes were then incubated for an additional 10 min. Volumes in each tube were noted, and cell suspensions were diluted 2-fold in PBS and placed in a hemacytometer chamber to obtain cell counts.
• culture medium was changed 24 hours prior to harvesting the cells for passaging. At the time of passage an aliquot of the culture medium was removed for hGH assay, and the cells were then harvested, counted, and reseeded. hGH levels are calculated after counting the harvested cells, and are expressed as ⁇ g hGH/24 hr/10 6 cells.
• mice for subcutaneous implantation of matrices, mice [M. usculus strains N:NIH(S) -nu/nu (nude; Taconic Farms, Germantown, NY) were given an intraperitoneal injection of avertin (solution of 2% w/v 2,2,2-tribromoethanol and 2% v/v 2-methyl, 2-butanol) at a dose of 0.0175 ml/g body weight. Anesthetized mice were placed in lateral recumbency, and the skin prepped with alcohol and Betadine.
• HCM hybrid collagen matrices
• CM standard collagen matrices
• a 0.5 cm to 1 cm transverse incision was made on the animal's left flank.
• the subcutaneous space was enlarged by sharp dissection to an area slightly larger than the size of the matrix to be implanted.
• the matrix was placed horizontally in the subcutaneous space and spread evenly with the use of Millipore forceps.
• the incision was closed, using stainless steel surgical staples.
• Blood was collected by retroorbital bleed after placing the mouse in a large beaker containing methoxyflurane (Pittman-Moore) until light anesthesia was achieved.
• Serum hGH levels were determined using the commercially available sandwich radioimmunometric assay described above. The assay was performed as described as recommended, except that control serum from untreated mice was used to obtain corrected cpm for generating the standard curve.
• CM and HCM were prepared for implantation into nude mice as described in Examples I and VI, using hGH- expressing HF165-24 cells.
• Tables 6 and 7 13 matrices of each type were prepared.
• HCM were produced with an inoculum density (ID) of 5xl0 6 HF165-24 cells per matrix, and standard collagen matrices (CM) were produced with an ID of 2xl0 6 HF165-24 per matrix. Fewer cells were used to inoculate the CM since these matrices do not support as high a cell density as HCM (see Examples V and VI) .
• HCM-implanted animals maintained substantially higher serum hGH levels than did CM-implanted animals for 186 days post-implantation. Animals implanted with HCM in Experiments 2 and 3 showed similarly high serum hGH levels.
• hybrid matrices of the invention would be prepared for implantation in humans as follows:
• the desired cells are harvested from tissue culture dishes and processed for the production of HCM or PCHCM by any of the methods described in Examples I-IV.
• the dosage for a given patient i.e. the physiologically effective quantity of therapeutic product produced by the matrix
• the quantity of the therapeutic product produced in the patient may also be varied by exposing the cells in the matrix to a pharmacologic or physiologic signal which alters expression of the therapeutic gene.
• the therapeutic gene is under the control of a glucocorticoid-responsive promoter
• a drug such as dexamethasone
• matrices with significantly higher cell densities (as produced by incorporating, for example, ascorbic acid 2-phosphate) would result in a smaller number of matrices needed for a given patient.
• a larger petri dish (> 150 mm diameter) may be used as a mold to produce larger matrices which could be either implanted directly or cut into smaller pieces which are implanted.
• the matrices Prior to implantation, the matrices may be stored or shipped in growth medium or any other solution which allows the cells to remain viable. Alternatively, the matrices may be cryopreserved by freezing in an appropriate freezing medium, which can be washed away prior to implantation.
• Matrices may be implanted in a variety of sites, including, but not limited to, subcutaneous, intraperitoneal, intrasplenic, intraomental, inguinal, intrathecal, intraventricular, and intramuscular sites, as well as within lymph nodes or within adipose tissue.
• HCM hybrid collagen matrices
• HCM HCM
• a number of these HCM can be aseptically transferred to a sterile Microcarrier Spinner Flask (250-100 ml capacity) .
• These HCM are produced and maintained under conditions which maximize the viable cell density within each matrix. Typically this requires between 5 and 20 ml medium for every one ml of matrix volume.
• the protein production medium is formulated to comprise a minimum of undefined components (e.g., serum), and may include added factors intended to maximize the output of protein production per cell.
• the spinner flasks are placed into a 37° + 1°C, 5% + 1% C0 2 humidified incubator on a magnetic stir platform set for 30-70 rpm.
• the flask After 1-3 days, the flask is transferred to a class 100 biological safety cabinet, and the production medium containing the expressed protein is aseptically drawn off without disturbing the settled matrices. An equivalent volume of fresh protein production medium is added to the flask, and the flask is returned to the stir platform within the incubator. 2.
• the matrices described in (1) above may be aseptically transferred into a 1-5L bioreactor (e.g, Brunswick) with a controllable stirring impeller shaft. Production medium level is set by the control system of the bioreactor. Medium harvesting and replenishment is controlled within a sterile closed loop system to minimize contamination.
• the matrices are formed from the constituent components and allowed to gel within a tissue culture roller bottle.
• the bottles are incubated in a static upright position until contraction of the matrix results in a free-floating structure (3-5 days) .
• Growth medium is then replenished, and the bottles are gassed with 5% C0 2 and placed into a roller apparatus within a 37°C incubator.
• Growth medium is replenished every 2-3 days until HCM are mature (10-25 days total incubation) , at which time the HCM are exposed to protein production medium.
• the bottles are transferred to a class 100 biological safety cabinet and the production medium containing the expressed protein is aseptically drawn off without disturbing the matrices. An equivalent volume of fresh protein production medium is added to the bottle, which is returned to the roller apparatus.
• the constituents of the HCM can be aseptically introduced into sterile gas-permeable TeflonTM bags through a sealable port.
• the components are allowed to gel within the bag and take on the shape and conformation therein. Bags are incubated in 37° + l°C, 5% ⁇ 1% C0 2 humidified incubators. As the HCM contract and reduce in volume, the growth medium volume is adjusted to compensate. Medium harvesting and replenishment is accomplished through sterile-connect tube systems built into the bags.
• the use of ported incubators and extended tubing would allow for the design of a cyclic harvest/feed pumping system that could eliminate the need for removing the bags from incubators during a production run.
• the constituents of the HCM can be aseptically introduced into custom-designed thermoformed trays with a high volume capacity.
• the simplest conformation would be an open lidded rectangular tray with gas exchange capabilities designed for use in a C0 2 tissue culture incubator.
• Another design would include a closed loop system with ported access to the medium reservoir for controlled feeding and medium harvest, akin to a bioreactor chamber.
• the hybrid matrices of the invention are appropriate for delivery of a wide range of cellular products, including not only hGH, but also Factor VIII, Factor IX, erythropoietin (EPO) , albumin, hemoglobin, alpha-1 antitrypsin, calcitonin, glucocerebrosidase, low density lipoprotein (LDL) receptor, IL-2 receptor, globin, immunoglobulin, catalytic antibodies, the interleukins, insulin, insulin-like growth factor 1 (IGF- 1) , parathyroid hormone (PTH) , leptin, the interferons, the nerve growth factors, basic fibroblast growth factor (bFGF) , acidic FGF (aFGF) , epidermal growth factor (EGF) , endothelial cell growth factor, platelet derived growth factor (PDGF) , transforming growth factors, endothelial cell stimulating angiogenesis factor (ESAF) , angiogenin, tissue
• EPO
• the cells embedded in the matrix can be pancreatic beta cells which naturally secrete insulin in response to a rise in blood glucose, and which therefore can supplement an inadequate insulin response in a diabetic or pre-diabetic patient.
• they can be any type of cell genetically engineered to express and secrete high levels of a needed polypeptide, such as a clotting factor, within the patient.
• Such a construct may be under the control of a constitutively activated promoter, or of an appropriately physiologically or pharmacologically regulated promoter.
• the collagen gel portion of the matrix can consist entirely of insoluble collagen fibrils, or can contain other components in addition to collagen: e.g., agarose; alginate; a glycosaminoglycan such as hyaluronic acid, heparin sulfate, dermatan sulfate, or chondroitin sulfate; a sulfated proteoglycan; fibronectin; la inin; elastin; fibrin; or tenascin.
• Such components contribute to the structural stability of the hybrid matrices of the invention, and/or provide additional attachment capacity for the cells in the matrices and the host tissue at the site of implantation. They would be incorporated into the matrices by mixing with the collagen solution prior to gelling.
• cytokines and/or growth factors which are useful for optimizing maintenance of the cells or promoting beneficial interaction with host tissue (e.g. , vascularization) , including bFGF, aFGF, endothelial cell growth factor, PDGF, endothelial cell stimulating angiogenesis factor (ESAF) , leukotriene C 4 , prostaglandins (e.g., PGE X , PGE 2 ) , IGF-1, GCSF, angiogenin, TGF- ⁇ , TGF-,5, ascorbic acid, EGF, and oncostatin M.
• host tissue e.g. vascularization
• bFGF e.g., vascularization
• aFGF endothelial cell growth factor
• PDGF endothelial cell stimulating angiogenesis factor
• leukotriene C 4 e.g., leukotriene C 4
• prostaglandins e.g., PGE X , PGE 2
• the cells may be genetically engineered to express the desired product.
• the cells of the matrix may be cotransfected with a DNA encoding an angiogenesis factor and a DNA encoding a second, therapeutic protein, or with a single vector encoding both types of proteins linked to suitable expression control sequences.
• the collagen used in the gel may be any suitable type (e.g., type I-XI) , or a mixture of any two or more.
• Fibers may be placed in the mold prior to gelling of the collagen, so that they become an integral part of the matrix and contribute to the sturdiness and handling convenience of the matrix.
• the fibers would be made principally of collagen (e.g.
• a non ⁇ collagenous material such as nylon, dacron, polytetrafluoroethylene (Gore-Tex'" or TeflonTM), polyglycolic acid, polylactic/polyglycolic acid mixture (VicrylTM), polystyrene, polyvinylchloride co-polymer, cellulose (e.g., cotton or linen), polyester, rayon, or silk.
• the fibers may be woven into a mesh or cloth, or used as individual threads.
• microspheres consisting primarily of another type of collagen, polystyrene, dextran (e.g., CytodexTM , Pharmacia) , polyacrylamide, cellulose, calcium alginate, latex, polysulfone, glass (coated with a substance such as collagen which promotes cellular adherence) , or combinations of collagen with any of the above.
• dextran e.g., CytodexTM , Pharmacia

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