JP2010275401A - Porous bead - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for removing blood cells in the blood simply and efficiently without being followed by blood coagulation. <P>SOLUTION: A porous bead concerned in the embodiment comprises a porous body formed of a synthetic polymer resin and has a plurality of holes on the surface. The porous body has a diameter, for example, of 1.5-3 mm. The porous body has an aperture ratio on the surface of preferably 20% or more. The proportion of the holes with diameters of 2-7 μm is preferably 80% or more among the holes present on the surface of the porous body. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bead for removing blood cells.

  For treatment of IBD (Inflammatory Bowel Disease) such as ulcerative colitis and Crohn's disease, in addition to anti-inflammatory treatment with drugs and resection of the inflamed area (in the case of ulcerative colitis), LCAP (lymphocytes) Elimination therapy) and blood cell elimination therapy by GCAP (granulocyte removal therapy) are known. Although the mechanism by which this blood cell removal therapy works is not clear, leukocytes (lymphocytes, granulocytes, etc.) activated for some reason are involved in inflammation of the disease. It is considered that removal of these leukocytes suppresses inflammation and has a therapeutic effect.

  According to recent findings, not only the above-mentioned leukocytes are involved in inflammation of the disease in IBD, but also the blood concentration of activated platelets is increased (> 400,000 / μL, normal value: 4 to 60,000 / μL), it has become clear that activated platelets are also greatly involved. Rather, platelets are first activated for some reason (genetic factors, environmental factors (stress), etc.), and various inflammatory mediators released by platelets act on the above leukocytes to enhance the inflammatory response. (Silvio Danese, et al Platelet in Inflammatory Bowel Disease: Clinical, Pathogenic, and Therapeutic Implications Am. J. Gastroenterol 2004; 938-945). In such diseases, embolization due to platelet-derived microthrombi has been observed in blood vessels at the site of inflammation, suggesting that platelet activation is involved in the worsening of IBD symptoms. (AJ Wakefield, et al Pathogenesis of Crohn's Disease: Multifocal Gastrointestinal Infraction, The Lanset Saturday 4 November 1989 1057-1062).

  Therefore, a treatment for positively removing platelets for IBD has been attempted. In IBD blood purification therapy, there is a centrifugal separation method in addition to LCAP and GCAP. This is to centrifuge the patient's blood and remove specific blood cells using the difference in specific gravity of blood cells, and is generally used to remove leukocyte fractions such as lymphocytes in the treatment of IBD. . However, in some facilities, focusing on the function of platelets in IBD, platelet removal therapy using a centrifuge has been achieved with certain results.

As for LCAP, a cell sover manufactured by Asahi Kasei Medical is known. However, the product is a lymphocyte remover (this fiber can be used by attaching a polyester extra fine fiber having a fiber diameter of 1 to 3 μm to a column in a non-woven form. It is known that platelets also remove about 35% of the extracorporeal circulation volume, despite the product intended to be adsorbed onto the body. There is also a report that when this was used for ulcerative colorectal patients, suppression of platelet activation was observed (Non-patent Document 1).

K. Fukunaga, et al, Activated Plateles as a Possible Early Marker to Predict Clinical Efficacy of Leukocyteapheresis in Severe Ulceratice Colitis Patients: J Gastroenterol 2006; 41: 524-532

As described above, it is considered that the platelet removal therapy functions effectively in the IBD treatment, but the conventional methods have some problems. That is,
(1) Platelet removal therapy using a centrifuge has a problem that the apparatus is complicated and expensive.

(2) In addition, the removal method using non-woven ultrafine fibers cannot remove a sufficient amount of platelets, and depending on the blood state, it is difficult to secure blood flow and blood coagulation occurs in the column. There are also difficult to use.

  The present invention has been made in view of these problems, and an object thereof is to provide a technique capable of easily and efficiently removing blood cells in blood without accompanying blood coagulation.

  One embodiment of the present invention is a porous bead. The porous beads are made of a synthetic polymer resin and are made of a porous body having a plurality of pores on the surface, and the porosity of the surface of the porous body is 20% or more.

  According to the porous bead of the said aspect, a blood cell can be easily and efficiently removed from the blood, without accompanying blood coagulation.

  In the porous beads of the above aspect, the proportion of pores having a diameter of 2 to 7 μm among the pores existing on the surface of the porous body may be 80% or more.

  Further, the synthetic polymer resin may include a polyarylate resin having a repeating unit represented by the following chemical formula (1) and a polyethersulfone resin having a repeating unit represented by the following chemical formula (2) or chemical formula (3).

In the chemical formula (1), R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms, and R1 and R2 may be the same or different.

In the chemical formula (2), R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms, and R3 and R4 may be the same or different.

Moreover, the porous beads of any of the above embodiments may be used for removing platelets in blood.

  According to the present invention, blood cells in blood can be easily and efficiently removed without blood coagulation.

It is the schematic of the porous bead manufacturing apparatus used for manufacture of a porous bead. FIG. 2A and FIG. 2B are scanning electron microscope images of the porous beads according to the example.

  The porous beads according to the embodiment are made of a synthetic polymer resin and are made of a porous body having a plurality of pores on the surface. The diameter of the porous body is, for example, 1.5 to 3 mm. The synthetic polymer resin is preferably a granular polymer.

  The porosity of the surface of the porous body is preferably 20% or more. If the aperture ratio is less than 20%, the platelet removal effect is reduced. By setting the aperture ratio to 20% or more, platelets can be more efficiently removed.

  Moreover, it is preferable that the ratio of the hole whose diameter is 2-7 micrometers among the holes which exist in the surface of a porous body is 80% or more. By setting the diameter of the pores on the surface of the porous body to 2 to 7 μm, platelets are taken in and captured by the porous layer on the surface of the porous beads on the principle of size exclusion. Since the size of platelets is usually 1 to 2 μm, if the diameter of the pores on the surface of the porous body is smaller than 2 μm, the platelets are not taken into the pores of the porous body. On the other hand, when the pore diameter on the surface of the porous body is larger than 7 μm, blood cells other than red blood cells such as red blood cells and white blood cells are taken into the pores of the porous body, and the ability to remove platelets decreases.

  The synthetic polymer resin forming the porous body contains a polyarylate resin and a polyethersulfone resin.

  The polyarylate resin is a resin having a repeating unit represented by the following chemical formula (4). The number average molecular weight of the polyarylate resin is preferably 20,000 to 30,000. If the number average molecular weight of the polyarylate resin is larger than 30,000, it becomes difficult to form an appropriate pore structure because the pore size of the porous body becomes too large or the variation in pore size becomes large. On the other hand, if the number average molecular weight of the polyarylate resin is less than 20,000, the pore diameter of each layer becomes too small, or the strength of the porous body becomes low, making it difficult to form an appropriate pore structure. .

In the chemical formula (4), R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms, and R1 and R2 may be the same or different. Examples of R1 and R2 include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Preferred R1 and R2 are methyl groups.

  The polyarylate resin is not particularly limited as long as the repeating unit represented by the chemical formula (4) is a main repeating unit, and may contain other repeating units as long as the object of the present invention is not impaired.

  The polyethersulfone resin is a resin having a repeating unit represented by the following chemical formula (5) or chemical formula (6). The number average molecular weight of the polyethersulfone resin is preferably 15,000 to 30,000. If the number average molecular weight of the polyethersulfone resin is larger than 30,000, the pore size of the porous body becomes too large or the variation in the pore size becomes large, making it difficult to form an appropriate membrane structure. On the other hand, if the number average molecular weight of the polyarylate resin is smaller than 15,000, it is difficult to form an appropriate pore structure because the pore diameter of the porous body becomes too small or the strength of the porous body itself becomes low. become.

In the chemical formula (5), R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms, and R3 and R4 may be the same or different. Examples of R3 and R4 include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Preferred R1 and R2 are methyl groups.

  The surface of the porous body is preferably hydrophobic. By making the surface of the porous body hydrophobic, leukocytes can be adsorbed on the surface of the porous body by hydrophobic interaction. Since the synthetic polymer resin composed of the polyarylate resin and the polyethersulfone resin described above is hydrophobic, it is suitable as a material for the porous body.

  The porous beads according to the embodiment are preferably used for platelet removal therapy. Specifically, blood cells, particularly platelets, can be removed from the blood by filling the column with the porous beads according to the embodiment and flowing the blood through the column. In this case, by filling the column with the porous beads, a flow path is formed between the adjacent porous beads and the blood flow is easily secured, so that the occurrence of blood coagulation is suppressed. Furthermore, blood cells, particularly platelets, can be easily and efficiently removed from blood without using a complicated device.

(Porous beads manufacturing method)
The manufacturing method of the porous bead concerning embodiment is demonstrated. First, polyethersulfone resin (hereinafter referred to as PES, grade 4800P, number average molecular weight 21,000) and polyarylate resin (hereinafter referred to as PAR, number average molecular weight 25,000) and N-methyl-2-pyrrolidone (hereinafter referred to as NMP) To prepare a polymer solution (stock solution). The mass mixing ratio of PES, PAR, and NMP was set to 7.5: 7.5: 85.0. A mixture of 50% NMP in water was used as the coagulation liquid. The polymer solution was dropped from a nozzle having an inner diameter of 0.25 mm and an outer diameter of 0.50 mm at a height of about 20 cm from the liquid surface of the coagulation liquid tank (see FIG. 1). After sufficiently coagulating in the coagulation liquid, it was washed with distilled water to obtain porous beads having a diameter of about 2 mm. The beads were immersed in a 95% NMP solution for 30 minutes to adjust the pores on the surface of the beads to obtain porous beads.

  FIG. 1 is a schematic view of a porous bead manufacturing apparatus 100 used for manufacturing porous beads. The stock solution stored in the stock solution tank 110 is supplied to the nozzle 130 by the pump 120. The stock solution supplied to the nozzle 130 is dropped from the nozzle 130. Below the nozzle 130, a coagulating liquid bath 140 in which the coagulating liquid is stored is provided. The coagulating liquid bath 140 is provided with a rotating body (not shown) that causes a spiral flow in the coagulating liquid.

  An overflow pipe 142 is attached to the upper part of the coagulating liquid bath 140. When the liquid level of the coagulating liquid stored in the coagulating liquid bath 140 reaches the attachment port of the overflow pipe 142, the overflowed coagulating liquid flows through the overflow pipe 142 and is collected in the coagulating liquid collection tank 144. In addition, it is preferable to provide a mesh 143 whose opening is smaller than the diameter of the porous bead 150 generated in the coagulation liquid bath 140 at the attachment port of the overflow pipe 142. According to this, the porous beads 150 are prevented from entering the coagulating liquid recovery tank 144 as foreign matter.

  The coagulation liquid collected in the coagulation liquid recovery tank 144 is pumped up using the coagulation liquid circulation pump 146 and stored again in the coagulation liquid bathtub 140. The amount of coagulating liquid supplied from the coagulating liquid recovery tank 144 to the coagulating liquid bathtub 140 is detected by the flow meter 147, and an appropriate amount is supplied to the coagulating liquid bathtub 140 using the coagulating liquid supply amount adjusting valve 148. Thus, since the coagulating liquid can be effectively used by circulating the overflowing coagulating liquid, the manufacturing cost of the porous beads 150 can be suppressed.

  The stock solution dropped from the nozzle 130 toward the coagulating liquid bath 140 is solidified into a spherical shape in the coagulating liquid flowing in a spiral shape, and the porous beads 150 are formed. By dropping the stock solution into the coagulating liquid flowing in a spiral shape, the spherical porous beads 150 can be obtained more stably and with a high yield.

  The solidified porous beads 150 are discharged from the lower portion of the coagulation liquid bath 140 and are held by the sieve 160 having a smaller opening than the diameter of the porous beads 150. The amount of the coagulating liquid including the porous beads 150 discharged from the coagulating liquid bath 140 is appropriately adjusted by the coagulating liquid discharge amount adjusting valve 170. The coagulation liquid discharged from the coagulation liquid bath 140 together with the porous beads 150 is recovered in the coagulation liquid recovery tank 144 and reused.

(Measurement of porosity of porous beads)
Here, a method for measuring the porosity of the porous beads will be described. First, the surface of the porous bead is photographed at a magnification of 1,500 using a scanning electron microscope (Hitachi S-3000).

  The pore diameter and number are counted in 4 fields (1 field: 65.5 μm × 87.3 μm) for one porous bead. Similar measurements are performed on 5 porous beads (20 fields total). The hole area ratio is calculated using the following formula.

Open area ratio = (total area of holes) / (area of one field of view) × 100 (%)
(Example)
The porous beads according to the example have a pore structure in which the porosity is 21.7% and the proportion of pores having a diameter of 2 to 7 μm is 80.9% among the pores existing on the surface of the porous body. 2A and 2B are scanning electron microscope images of the porous beads according to the example (FIG. 2A: 50 times, FIG. 2B: 500 times).

(Comparative example)
Beads used in a commercially available extracorporeal circulation column (Adacolumn (registered trademark), manufactured by JIMRO) were taken out and used as cellulose triacetate beads according to Comparative Example 1. The beads of Comparative Example 1 have a surface shape with no holes on the surface, a center average roughness Ra value of 0.2 μm to 10 μm, and a bumpy average interval Sm value of 5 μm to 200 μm.

(Measurement of platelet capture rate)
15 mL of 5 mL of heparinized blood (10 IU / mL) collected from 2 subjects (healthy subjects), 4 mL of Example beads (diameter of about 2 mm), and cellulose triacetate (CTA) beads of the same shape (Comparative Example 1) of 15 mL In a plastic tube, a gentle shaking (30 rpm) was performed at 37 ° C. for 30 minutes. Further, as Comparative Example 2, the same treatment was performed on 5 mL heparinized blood without beads in the same tube.

  The white blood cell count (WBC), red blood cell count (RBC), and platelet count (RLT) of these blood were counted using a multi-item automatic blood cell counter (Sysmex KX-21). Tables 1 and 2 show the results of experiments using heparinized blood collected from each subject.

As can be seen from Tables 1 and 2, in Example and Comparative Example 1, the number of white blood cells, red blood cells, and platelets are all reduced compared to Comparative Example 2, and it can be seen that blood cells are removed. When comparing the example and the comparative example, both the white blood cell count and the red blood cell count are slightly decreased in the example compared to the comparative example. On the other hand, in the Example, it turns out that the number of platelets has decreased dramatically to half or less of the comparative example. That is, it was confirmed that the porous beads of the example had an extremely large ability to remove platelets compared to Comparative Example 1.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. Embodiments to which such modifications are added

100 porous bead manufacturing apparatus, 110 stock solution tank, 120 pump, 130 nozzle, 140 coagulation liquid bath, 144 coagulation liquid recovery tank, 150 porous beads.

Claims (4)

It is made of a synthetic polymer resin and consists of a porous body with a plurality of pores on the surface.
A porous bead having a porosity of 20% or more on the surface of the porous body.   2. The porous bead according to claim 1, wherein a ratio of pores having a diameter of 2 to 7 μm among pores existing on the surface of the porous body is 80% or more. The synthetic polymer resin includes a polyarylate resin having a repeating unit represented by the following chemical formula (1) and a polyethersulfone resin having a repeating unit represented by the following chemical formula (2) or chemical formula (3). The porous bead according to claim 1 or 2.
In the chemical formula (1), R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms, and R1 and R2 may be the same or different.
In the chemical formula (2), R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms, and R3 and R4 may be the same or different.
  The porous bead according to any one of claims 1 to 3, which is used for removing platelets in blood.