JP2545556B2 - Frozen preservation blood washing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a frozen preservation blood washing method.
More specifically, the present invention relates to a cryopreservation blood washing method for efficiently and continuously removing a protective solution added to blood to be cryopreserved.

(Prior art) In recent years, blood transfusion is a method of transfusing blood containing all the components obtained by donating blood, so-called whole blood, and is a component transfusion in which only the blood components required by the patient are fractionated from the blood of another person Have moved to. Such component transfusion has less burden on the circulatory system compared with whole blood transfusion, and avoids and reduces immunological side effects. Since only large amounts of necessary components can be transfused at one time, the percentage of whole blood is small. It is possible to expect sufficient effects even with ingredients, and it is possible to effectively use ingredients that are not necessary for one patient for other patients [Tanaka and Shimizu, Comprehensive clinical practice vol.35, N
O.11 (1986)], etc., but this component transfusion is not sufficient from the viewpoint of avoiding infection and sensitization, which are the two major side effects associated with transfusion.
Infection with AIDS, ATLA, etc., or sensitization, especially in children, has been regarded as a problem, and preventive measures against these have been earnestly desired.

Recently, as a method capable of solving such a problem, an autologous blood transfusion method of transfusing a blood sampled in advance has attracted attention. If you use your own blood, problems such as virus infection and sensitization as described above do not occur essentially, and even an extremely rare blood type person can be prepared for an emergency.

In such an autologous blood transfusion method, the collected blood is separated into its components and then stored frozen.
Currently, blood can be stored for up to 42 days if it remains a liquid, but such cryopreservation allows semi-permanent storage, thus establishing a long-term safe blood transfusion system.

(Problems to be Solved by the Invention) By the way, if blood that has been separated into its components is directly frozen and stored, each component such as red blood cells, white blood cells, and platelets will be destroyed. It is necessary to add a protective solution to. At present, this protective solution varies depending on each research institution, etc., and of course depending on the target blood component, but most of them contain glycerin, dimethyl sulfoxide, etc. When returning the stored blood to the body, it is necessary to prepare a deprotection liquid by diluting and washing the stored blood after thawing.

Examples of the dilution / washing method currently performed include, for example, red blood cell concentrated liquid, Huggins liquid (glycerin 79%, glucose 8%, fructose 1%, EDTA-2.
50% when slowly frozen by adding sodium salt 0.3%)
First wash with glucose solution + 5% fructose solution, second wash with 5% fructose solution, third wash with 5% fructose solution, fourth wash with physiological saline, then saline Re-floating to [Massachusetts General Hospital (Haggin
g), National Fukuoka Central Hospital (Sumida)] In addition, when red blood cell concentrate was added to a rho solution (28% glycerin, 3% mannitol, 0.65% sodium chloride) and rapidly frozen, the first centrifugation was continued. Discard the supernatant, add 0.45% NaCl solution containing 15% mannitol for the second time, and discard the supernatant after centrifuging. For the third and fourth times, add 0.9% NaCl solution and discard the supernatant after centrifuging. Finally, the method of resuspending in saline is adopted [New York Blood Center (Rowe)].

As described above, currently, the stored blood is diluted / washed by the badge method, and requires centrifugation or centrifugation. The recovery efficiency of the components was also not sufficient.

Therefore, it is an object of the present invention to provide a novel frozen blood preservation washing method. It is another object of the present invention to provide a frozen preservation blood washing method for efficiently and continuously removing a protective liquid added to blood to be frozen and preserved. It is another object of the present invention to provide a frozen preservation blood washing method that enables an aseptic washing operation. It is another object of the present invention to provide a frozen preserved blood washing method having a high blood component recovery efficiency.

(Means for Solving the Problems) The above-mentioned objects are to provide a first fluid introduction port and an outlet port in which a large number of porous hollow fiber membranes are arranged in a housing, and the inner space of the hollow fiber membranes is provided in the housing. To form a first fluid circulation space, while a space surrounded by the inner peripheral surface of the housing and the outer surface of the porous hollow fiber membrane communicates with a second fluid inlet and outlet provided in the housing. By using a plurality of blood washing devices each of which forms a second fluid passage space that is partitioned from the first fluid passage space, either the first fluid passage space or the second fluid passage space of each blood washing device is used. Are connected in series to form a blood flow path, and the continuous blood flow paths are arranged in a substantially straight line to send blood to be washed, while a plurality of independent second fluid flow spaces or Each fluid distribution space is different Alternatively, it is achieved by a method for washing frozen preserved blood, which is characterized in that a washing solution of the same kind is fed and a washing operation in several steps is continuously performed.

In the method for washing frozen stored blood of the present invention, a mode in which blood is sent in the direction of gravity is preferably shown. Further, in the method for washing frozen stored blood of the present invention, a mode in which blood is sent in the direction opposite to the direction of gravity is preferably shown. Furthermore, in the method for producing cryopreserved blood of the present invention, the porous hollow fiber membrane arranged in the blood washing device has a hydrophilic compound grafted with γ rays on at least the inner surface and the inner surface of the pores of the hydrophobic porous hollow fiber membrane. A preferred embodiment is one in which a hydrophilic thin layer is formed.

(Operation) Therefore, as described above, the frozen preservative blood washing method of the present invention includes the first fluid circulation space or the second fluid circulation space of a plurality of blood washing apparatuses in which a large number of porous hollow fiber membranes are arranged. The spaces are connected in series to form a blood flow path, and the continuous blood flow paths are arranged in a substantially straight line to send blood to be washed, while a plurality of independent second fluid flow spaces or Cleaning fluids of different types or the same type are passed through the one fluid circulation space.

As described above, in the cleaning method of the present invention, the stored blood after thawing in the blood cryopreservation system is cleaned using the porous hollow fiber membrane. That is, in the cleaning method of the present invention, the stored blood or the cleaning liquid is sent to the internal space (first fluid circulation space) of the large number of porous hollow fiber membranes arranged in the blood cleaning device as described above, while, A cleaning liquid or stored blood is made to flow in a space (second fluid circulation space) formed by the outer surface of the porous hollow fiber membrane and the inner peripheral surface of the housing, and a blood protection liquid component such as glycerin contained in the stored blood. Since it is permeated and removed to the washing liquid side through the hollow fiber membrane due to the difference in concentration, it does not require complicated treatment such as centrifugation or centrifugation and may have a bad influence on blood components, and is simple and The cleaning process can be performed efficiently.

Further, in the blood cryopreservation system, since the concentration of the protective liquid component such as glycerin added to the preserved blood to be removed is high and contains plural kinds of components, the porous hollow fiber membrane as described above is used. Even if the blood cleaning device that is arranged is used, not only is the cleaning efficiency poor if only one kind of cleaning liquid is used in one blood cleaning device, but also sufficient cleaning is possible even if the effective length of the blood cleaning device is increased. However, in the frozen preservation blood washing method of the present invention, the space in which blood flows in the plurality of blood washing devices (first fluid circulation space or second fluid circulation space).
However, since they are connected in series, the blood processed by the first blood cleaning device is continuously sent to the second blood cleaning device without being exposed to the external environment, and the second blood cleaning device Blood can be sequentially and aseptically processed in a closed system in several steps by a plurality of blood cleaning devices, such as being processed in the device. In the frozen blood cleaning method of the present invention, since the cleaning liquid system in each blood cleaning device is independent, it is possible to use different cleaning liquids in each device (of course, the same kind of cleaning liquid can also be used. .) Can be used for efficient cleaning.

In addition, in the cryopreservation blood washing method of the present invention, since the blood circulation spaces of the plurality of blood washing devices are arranged substantially linearly, the flow of blood passing through this washing circuit is almost the same. It is possible to keep the damage to blood components in the washing process to a minimum, without the risk that the blood components will be constantly maintained and the blood components will not be burdened.

Hereinafter, the present invention will be described in more detail based on embodiments.

FIG. 1 is a schematic view showing an example of a washing circuit in the frozen preservation blood washing method of the present invention, and FIG. 2 is a schematic sectional view showing an example of a blood washing apparatus used in the frozen preservation blood washing method of the present invention. Is.

In the cryopreservation blood washing method of the present invention, as shown in FIG. 2, a large number of porous hollow fiber membranes 12 are arranged in the housing 11, and the internal space of the hollow fiber membranes 12 is provided in the housing 11. A first fluid flow space 15 is formed in communication with the first fluid inlet port 13 and the outlet port 14, while the space surrounded by the inner peripheral surface of the housing 11 and the outer surface of the porous hollow fiber membrane 12 is a housing. Second fluid inlet 16 and outlet 17 provided
A blood cleaning apparatus that forms a second fluid circulation space 18 that is communicated with the first fluid circulation space 15 and is partitioned from the first fluid circulation space 15 (in this example, is partitioned by a partition wall 19 formed of a potting agent). It uses a plurality of 10.

As the porous hollow fiber membrane 12 arranged in such a blood cleaning device 10, a hydrophilic porous hollow fiber membrane such as a copper ammonia regenerated cellulose membrane conventionally used for hemodialysis can be used. When such a hydrophilic porous membrane is used, water or 5-10% glycerin aqueous solution filled in the blood washing device until the time of use to shorten the priming time is used, or the hydrophilic porous hollow fiber The membrane immediately swells when it comes into contact with stored blood or a washing solution, which causes the pores of the porous membrane to be blocked or reduced, so that the protective solution components such as glycerin contained in the stored blood are permeated and removed. In addition, since such a hydrophilic porous hollow fiber membrane is not sufficient in terms of physical properties such as mechanical strength, it is preferably sparse. Sex porous hollow fiber least interior and hydrophilic compounds in the hole inner surface formed by a hydrophilic thin layer formed by grafting is formed by γ-ray porous hollow fiber membrane of the membrane are preferred.

The hydrophobic porous hollow fiber membrane used as a substrate in this porous hollow fiber membrane is not particularly limited, and examples thereof include polyolefin-based, polyester-based, polyamide-based, polyurethane-based, poly (meth) acrylate-based, poly (meth) ) A variety of hydrophobic synthetic resins such as acrylonitrile-based, polysulfone-based, polyvinyl chloride-based, and polymer blends thereof can be used, but from the viewpoint of γ-ray resistance, mechanical strength, etc., a polyolefin-based one is particularly preferable,
Most preferably, it is polypropylene. Further, it should have sufficient hydrophilicity as a hydrophilic compound to be grafted by γ-rays on at least the inner surface and inner surface of the pores of the hydrophobic porous hollow fiber membrane as described above, and desirably have high physiological safety. If not particularly limited, for example, water-soluble alcohols such as methanol, ethanol, glycerin, low-molecular-weight sugars such as fructose, glucose, mannitol, alanine, arginine, cysteine and water-soluble amino acids, oxalic acid, malonic acid, succinic acid. Dicarboxylic acids such as, glyoxylic acid, pyruvic acid, keto acids such as acetoacetic acid, glycols, lactic acid, hydroxy acids such as α-hydroxybutyric acid, acrylic acid, maleic acid, unsaturated carbonyl compounds such as methacrylic acid and its sodium or Potassium salts and the like can be used, but particularly preferably, It is Lyserine. When glycerin is used, a concentrated glycerin solution may be used.
A glycerin aqueous solution having a concentration of% may be used. To form a hydrophilic thin layer composed of such a hydrophilic compound on the inner surface and inner surface of the pores of the hydrophobic porous hollow fiber membrane as described above, for example, a hydrophilic compound is formed in the inner space of the hydrophobic porous hollow fiber membrane. Then, the hydrophobic porous hollow fiber membrane may be irradiated with γ-rays in this state. The irradiation conditions for gamma rays are 0.1 to 25 Mra.
d, preferably about 2.5 to 10 Mrad.
Then, after γ-ray irradiation, excess hydrophilic compound that has not been graft-bonded to the hydrophobic porous membrane is discharged from the internal space of the hydrophobic porous membrane, and sterile distilled water or physiological saline is used. By sufficiently removing the hydrophilic compound attached and remaining in the inner space of the hydrophobic porous membrane, a desired blood washing hollow fiber membrane can be obtained. Further, such γ-ray irradiation, after assembling the hydrophobic porous hollow fiber membrane in the blood washing device as described below, filled with the hydrophilic compound as described above, if performed to the entire device, At the same time, it is highly desirable that the blood cleaning device can be sterilized by γ-rays. When a circuit in which a plurality of blood cleaning devices are connected is formed as shown in FIG. 1 and then the hydrophilic compound is filled in and the irradiation with γ-rays is performed, the circuits are simultaneously irradiated with γ-rays. It is highly desirable because it can be sterilized. Since the hydrophilic thin layer formed in this manner is formed by grafting the hydrophilic compound as described above on the inner surface and the inner surface of the pores of the hydrophobic porous hollow fiber membrane by γ-rays, it has sufficient hydrophilicity. Despite imparting the properties to the porous hollow fiber membrane, it does not substantially change the membrane structure of the hydrophobic porous membrane even if it is extremely thin and even in a wet state, and therefore stable permeation It shows the performance.

In the cryopreservation blood cleaning method of the present invention, the plurality of blood cleaning devices 10 having the above-described configurations are either the first fluid circulation space 15 or the second fluid circulation space 18 of each blood cleaning device 10. Are connected in series, whereby a series of washing circuits forming a blood flow path communicating with each blood washing device 10 is assembled.

For example, in the washing circuit shown in FIG. 1, four blood washing devices 10 each having the structure shown in FIG.
The first fluid outlet port 14a of the blood cleaning device 10a and the first fluid inlet port 13b of the second blood cleaning device 10b are, for example, a connection tube 20a made of a flexible resin such as polypropylene or polyvinyl chloride. The first fluid outlet 14b of the second blood cleaning device, the first fluid inlet 13c of the third blood cleaning device 10c, and the first fluid outlet 14c of the third blood cleaning device.
And the first fluid inlet 13d of the fourth blood cleaning device 10d are connected in the same manner, and the first fluid flow space 1 of the first blood cleaning device 10a is connected.
5a, the first fluid circulation space 15b of the second blood cleaning device 10b, the first fluid circulation space 15c of the third blood cleaning device 10c and the fourth
A blood flow path is formed in communication with the first fluid circulation space 15d of the blood cleaning device 10d. On the other hand, each blood cleaning device 10
a, 10b, 10c, 10d second fluid circulation space 18a, 18b, 18c, 1
8d are independent of each other, and these are four independent washing liquid flow paths. In the embodiment shown in FIG. 1, the first fluid circulation spaces 15a, 15b, 15c, 15d of the blood cleaning devices 10a, 10b, 10c, 10d are communicated with each other, and the porous hollow fiber membrane 12
It is said that blood is sent to the insides of a, 12b, 12c, and 12d, but the second fluid circulation spaces 18a, 18b, 18c, and 18d of the blood cleaning devices 10a, 10b, 10c, and 10d are communicated with each other, and The structure may be such that blood is sent to the outside of the hollow fiber membrane. Further, the number of blood cleaning devices can of course be increased or decreased if necessary.

In the cryopreservation blood washing method of the present invention, the continuous blood flow paths of the washing circuit thus assembled are arranged substantially linearly. However, this is not particularly strict, and as long as the blood flow path does not bend in the opposite direction at all, it may be about the same direction throughout. In addition, if the gravity of the blood flow passage is constant on the blood flowing through the blood flow passage, the blood flow is from top to bottom in the vertical direction (the blood flow is in the gravity direction) and in the vertical direction. It may be arranged either from the bottom to the top (the blood flow is in the antigravity direction) or in the horizontal direction.

Then, the blood to be washed is sent to the blood flow passage of the washing circuit arranged in this way, and on the other hand, to a plurality of independent washing liquid flow passages (that is, the unconnected second fluid circulation space or first fluid circulation space). By feeding different cleaning liquids or the same cleaning liquid, it is possible to continuously carry out the cleaning operation in several stages. For example, taking the mode shown in FIG. 1 as an example, more specifically, first, the entire circuit is autoclaved or γ-sterilized prior to the cleaning process.
Sterilized by wire sterilization, etc., and the first blood cleaning device 10
Saline is flowed through the first fluid inlet 13a of a to prime the entire circuit. Then, each blood cleaning device 10a, 10
A predetermined cleaning liquid is supplied from the second fluid inlets 16a, 16b, 16c, 16d of b, 10c, 10d to the second fluid circulation spaces 18a, 18b, 18c, 1
8d and continues to be discharged from each of the second fluid outlets 17a, 17b, 17c, 17d. Each blood cleaning device 10a, 10b, 10c, 10d
The cleaning liquids used in the above may be of different kinds or of the same kind, if necessary. Then, in this way, each blood cleaning device 10a, 10b, 10
The flow rate of the cleaning liquid sent to the second fluid circulation spaces 18a, 18b, 18c, 18d of c and 10d is constant at a predetermined flow rate within the range of, for example, 10 ml to 50 / min, more preferably 100 ml to 5 / min. At this point, the thawed stored blood is fed through the first fluid inlet 13a of the first blood cleaning device 10a to, for example, 10 to 2000 ml / m 2.
In, more preferably, a predetermined flow rate within the range of 20 to 1500 ml / min is passed through the blood flow path. The blood sent to the blood flow path firstly has the first fluid circulation space 15a of the first blood cleaning device 10a.
While flowing through the inner space of the porous hollow fiber membrane 12a inside, due to the difference in concentration with the first washing liquid flowing through the second fluid circulation space 18a through the porous hollow fiber membrane 12a, After the predetermined protective liquid component contained is permeated and removed to a predetermined ratio, it is sent to the first fluid circulation space 15b of the second blood cleaning device 10b which is in communication therewith, and the porous material in the first fluid circulation space 15b. While flowing through the internal space of the hollow fiber membrane 12b, as in the above, through the porous hollow fiber membrane 12b, due to the concentration difference with the second washing liquid flowing through the second fluid flowing space 18b, After the remaining predetermined protective liquid component is permeated and removed to a predetermined ratio, it is sent to the second fluid circulation space 15c of the communicating third blood cleaning device 10c. In the same manner, in the third blood washing device 10c and the fourth blood washing device 10d, the remaining protective liquid component is permeated and removed, and in this way, a series of washing treatments in four stages is performed to completely deprotect. The liquefied blood is supplied to the first fluid outlet 14d of the fourth blood cleaning device 10d.
It will be taken out and used for blood transfusion.

The frozen preservation blood washing method of the present invention is carried out as described above, but the washing liquid and the pores of the porous hollow fiber membrane are used depending on the type of the blood component to be preserved and the protective liquid component to be added. Various component bloods such as red blood cell fraction, platelet fraction, white blood cell fraction (or lymphocyte fraction and granulocyte fraction), and bone marrow fraction, which have been cryopreserved by various methods by changing the characteristics. It is possible to apply to the washing method after thawing.

(Examples) Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 10000 polypropylene porous hollow fiber membranes having an inner diameter of 200 μm and a wall thickness of 10 μm (average pore diameter 1.0 μm, porosity 70%) were formed into a cylindrical shape of the blood washing device 10 as shown in FIG. It was placed in the housing 11, both ends were fixed by polyurethane potting material and the porous hollow fiber membrane 12 was assembled in the housing 11 to create a blood washing device 10 with an effective length of 230 mm and an effective membrane area of 1.6 m ² . . In this way, four blood cleaning devices 10 having the same structure were produced, and subsequently, as shown in FIG. 1, the first fluid outlets 14a, 14b, 14 of one device were manufactured.
By connecting the first fluid inlet ports 13b, 13c, 13d of the next device to c using the polyethylene connecting tubes 20a, 20b, 20c, the first fluid of the four blood cleaning devices 10a, 10b, 10c, 10d A cleaning circuit was created in which the distribution spaces 15a, 15b, 15c, 15d were connected in series. First blood cleaning device 10a of this circuit
Glycerin was caused to flow from the first fluid inlet 13a, and glycerin was filled in the internal space of the porous hollow fiber membrane 12 in each blood cleaning device 10a, 10b, 10c, 10d. In this state, the whole circuit was irradiated with γ-rays at an irradiation intensity of 8 Mrad. After irradiating with γ-rays, glycerin was eliminated from the system and further thoroughly washed with sterile physiological saline to remove glycerin remaining on the hollow fiber membrane. (Or each blood cleaning device 10a, 1
Glycerin is filled in 0b, 10c, and 10d, and the first fluid inlet 13
a, 13b, 13c, 13d and outlets 14a, 14b, 14c, 14d, and second fluid inlets 16a, 16b, 16c, 16d and second fluid outlets 17a, 17b, 17c, 17d are respectively sealed with caps. It is also possible to irradiate each of the blood washing devices 10a, 10b, 10c, and 10d with γ-rays at an irradiation intensity of 8 Mrad to make them hydrophilic, and then aseptically assemble them as shown in FIG. ) The stored blood was washed using the circuit thus treated. First, as preserved blood to be washed, equal volumes of Huggins solution (79% glycerin, 8% glucose, 1% fructose,
EDTA-2 sodium salt (0.3%) was added and a preserved red blood cell concentrate stored at -85 ° C was prepared and thawed at 40 ° C. On the other hand, the circuit is first arranged so that the first blood cleaning device 10a to the fourth blood cleaning device 10d are positioned substantially linearly from top to bottom in the vertical direction. Then, after priming the entire circuit with sterile saline, the second of each blood wash device 10a, 10b, 10c, 10d of the above circuit is
The cleaning liquid shown in Table 1 is supplied from the fluid inlets 16a, 16b, 16c, 16d at a flow rate of 500 ml / min to the respective second fluid circulation spaces 18a, 18b, 18
It flowed into c and 18d and continued to be discharged from the second fluid outlets 17a, 17b, 17c and 17d. When the flow rate of the cleaning solution becomes constant,
Store 400 ml of the stored blood thawed as above in the circuit above.
It was sent from the first fluid inlet 13a of the first blood cleaning device 10a at a flow rate of ml / min. The washed blood flowing through the circuit and flowing out from the first fluid outlet 14d of the fourth blood cleaning device 10d was collected. The time required for this cleaning treatment was 4.5 minutes. The recovery rate of red blood cells was determined by measuring the number of red blood cells before and after the washing treatment, and it was 95%, and glycerin contained in the blood after the washing treatment was 0.1 ppm,
It was virtually completely removed.

(Effects of the Invention) As described above, according to the present invention, a large number of porous hollow fiber membranes are arranged in the housing, and the internal space of the hollow fiber membranes is provided in the housing with the first fluid inlet and outlet ports. To form a first fluid circulation space, while a space surrounded by the inner peripheral surface of the housing and the outer surface of the porous hollow fiber membrane communicates with a second fluid inlet and outlet provided in the housing. By using a plurality of blood washing devices each of which forms a second fluid passage space that is partitioned from the first fluid passage space, either the first fluid passage space or the second fluid passage space of each blood washing device is used. Are connected in series to form a blood flow path, and the continuous blood flow paths are arranged in a substantially linear manner to send blood to be washed, while a plurality of independent second flow paths are provided.
A washing method for frozen stored blood characterized in that different kinds or same kinds of washing liquids are respectively sent to the fluid circulation space or the first fluid circulation space to continuously carry out a washing operation in several stages. With a high blood component recovery rate, the washing operation of frozen stored blood in several stages can be continuously and easily performed aseptically in a closed system, which greatly develops the frozen storage system of blood.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a battlefield circuit in the frozen preservation blood washing method of the present invention, and FIG. 2 is a schematic sectional view showing an example of a blood washing apparatus used in the frozen preservation blood washing method of the present invention. is there. 10,10a, 10b, 10c, 10d ... Blood cleaning device, 11,11a, 11b, 11
c, 11d …… housing, 12,12a, 12b, 12c, 12d …… porous hollow fiber membrane, 15,15a, 15b, 15c, 15d …… first fluid circulation space,
18,18a, 18b, 18c, 18d …… Second fluid distribution space, 20a, 20b, 20
c …… Connection tube.

Claims (4)

(57) [Claims] 1. A large number of porous hollow fiber membranes are arranged in a housing, and an internal space of the hollow fiber membranes is communicated with a first fluid inlet and outlet provided in the housing to form a first fluid circulation space. On the other hand, the space surrounded by the inner peripheral surface of the housing and the outer surface of the porous hollow fiber membrane is communicated with the second fluid inlet and outlet provided in the housing to form the first fluid flow space. Using a plurality of blood cleaning devices each of which forms a partitioned second fluid circulation space, and connecting either the first fluid circulation space or the second fluid circulation space of each blood cleaning device in series Forming a passage and arranging the continuous blood passages in a substantially linear manner to feed blood to be washed, while a plurality of independent second fluid circulation spaces or first fluid circulation spaces are of different types or the same type. The cleaning liquid of The method of cleaning frozen blood, characterized in continuously carrying out the cleaning operation over. 2. The method for washing frozen preserved blood according to claim 1, wherein the blood is sent in the direction of gravity. 3. The method for cleaning frozen preserved blood according to claim 1, wherein the blood is sent in the direction opposite to the direction of gravity. 4. A porous hollow fiber membrane arranged in a blood washing device has a hydrophilic thin layer obtained by grafting a hydrophilic compound by γ-rays on at least the inner surface and the inner surface of pores of the hydrophobic porous hollow fiber membrane. Claim 1 which is formed
Item 4. A method for washing frozen stored blood according to any one of Items 3 to 3.