JPS6122981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The human umbilical cord (umbilical cord) includes those that can be used for implantation of vascular systems and other ducts in mammals, including humans. In other words, the umbilical cord contains the so-called "Mr. Whartons"
1 artery and 2 surrounded by
Both can be used in various ways depending on the conditions at the time, such as in certain surgical procedures, such as transplantation, suturing of ducts, etc.

The venous artery excised from the umbilical cord can be used immediately as a graft, or if preserved by cooling or chemical methods, it can be used constantly. Sterility can also be maintained by antibiotics or other means. Of course, for such substances,
Although it has a low degree of antigenicity, it is possible to completely remove the antigenic substance by treating it with an enzyme.

Generally, the umbilical cord is coiled and twisted around its arteries. Therefore, in order to use them as implants, it is necessary to straighten them by mechanical or chemical means.

Furthermore, in order to use the venous artery as a graft, the "Mr. Whiten's Jewelry" within the umbilical cord must be flushed out with saline or removed directly by hand. After inserting the tapered shaft into the vein, the artery and vein are cut from the umbilical cord. As mentioned above, these venous arteries can be used as is or frozen. Further, the venous artery can be hardened using a tanning liquid or the like. The advantage of this treatment method is that the tanned venous artery can retain the shape of the shaft rod inserted into it. In this case, it is desirable to use gluteraldehyde as the tan skin liquid. Furthermore, before the venous artery tanned as described above is actually used as a graft, it is necessary to remove gluteraldehyde residues using a chemical agent such as glutamic acid. Curing using tan peel liquid or removing glutaraldehyde residue using glutamic acid or the like has the effect of lowering antigenicity and thrombogenicity.

Conduits such as the umbilical venous artery, which are used for suturing and reinforcing various conduits during surgical operations, have the following characteristics, even if they are fresh or have been stored for a certain period of time: There are advantages.

1. Easy to obtain.

2. Has almost no twisting and is highly flexible.

3. Strength, especially that smaller diameter conduits have greater strength.

4.It is extremely smooth and its inner wall is difficult to solidify.

5. It is difficult to be infected by external bacteria.

6. Must have low antigenicity.

7. The radius of the conduit can be adjusted depending on the purpose each time.

8. Sizes can be selected to match both large and small conduits.

9. Must be of sufficient length for any purpose.

10 Various shapes such as tapered or curved shapes can be used.

11 It is inert to the mesh support members for reinforcing large conduits.

12 It can be used as a skin graft when treating epidermal wounds such as trauma and burns.

Therefore, the first object of the present invention is to provide a novel material which can be used to supplement ductal systems, to strengthen various organs as a patch, to strengthen organ anastomoses, and to treat epidermal wounds. An object of the present invention is to provide an umbilical cord conduit graft.

A second purpose is to provide a novel method for using venous arteries excised from the umbilical cord in surgical transplantation procedures.

A third object is to provide a method for shaping a venous artery excised from the umbilical cord into a shape suitable for use in surgery.

The fourth purpose is to provide a method for preserving the venous artery so that it can be used immediately during surgery, and the fifth purpose is to create a conduit using the venous artery excised from the umbilical cord. The object of the present invention is to provide a conduit graft that is in the form of a shape or a patch and has low antigenicity and low thrombogenicity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The features and advantages of the present invention will be explained in detail below with reference to surgical examples or various embodiments performed using the implant according to the present invention and the accompanying drawings.

First, the transplant surgery example shown below relates to a so-called interposition surgery in which a conduit excised from a human umbilical cord is transplanted into an animal's subceliac artery.

In this example of surgery, a baboon (Binitus vulgaris) was used as the surgical subject. First, the baboon was anesthetized, kept under sterile conditions, its fur shaved, and a longitudinal incision was made down the middle of the baboon's abdominal cavity. The incision range is
It extends from the xythoid to the genital area, across the middle of the abdominal cavity and into the peritoneal cavity. The bleeding blood vessel was pinched with a clamp and sutured using 3-0 polyglycolic acid. The baboon was examined for abnormalities in its peritoneal cavity, intestines and other internal organs, and all were found to be normal.
The intestines and other internal organs were also wrapped with cloth and indexers to secure them in place. An incision was made in the peritoneum above the aorta, and blood flow in the aorta was stopped with a clamp. Furthermore, each artery in the lumbar region is pinched with a 3-0 clamp.
Silk sutures were used to stop blood flow in the part of the celiac aorta that runs from the infrarenal artery to the aortic bifurcation. In this way, the entire section of the celiac aorta was prepared for implantation of the umbilical cord conduit.

As described above, while on the one hand we are making all the preparations for the baboon's celiac aorta, on the other hand we are performing the surgical procedure 2.
After removing the umbilical cord of a human baby born hours ago, it was placed in sterile saline and packed in ice to prevent the cord's structure from collapsing. Before placing the umbilical cord on ice, the umbilical cord should be treated with a sterile choline solution containing antibiotics, particularly in this surgical example, a solution of 1% cephalosporin per 1 liter solution.
The umbilical cord was washed multiple times with a solution containing 25,000 units of bacitracin to completely flush out the blood in the umbilical cord duct, and the umbilical cord was washed again with a 1 percent heparin anticoagulant solution. Next, one side of the umbilical cord's venous tube, which will be used as a graft, is pinched with a clamp.
From the other end, insert the red rubber catheter (No. 14
French) was introduced and the venous tube was inflated. At this time, an approximately 5 cm long umbilical graft was cut out, an axial rod was introduced into the venous canal, and the remaining portion of the umbilical cord was discarded. The cut intravenous tube was then placed in the operating room under sterile conditions, while a 2,500 unit heparin solution was injected into the vein of the baboon to prevent blood clotting. Next,
After holding the baboon's celiac aorta close to the part to be resected with a clamp and cutting out a section approximately 3 cm long from the celiac aorta, the aorta and the umbilical cord venous canal were first separated by 6 cm. -0 Proline (single nylon suture) was used to complete the suture.

Furthermore, the aorta was washed to remove coagulated blood and debris, and the distal portions were anastomosed. Once the anastomosis was completed, the clamp that was pinching the aorta was removed.

There was no bleeding at all from the sutured area. In this case, although this is a rare occurrence in the past, when the umbilical cord is used, there is no bleeding at the suture site due to its strength and the self-contracting property of dielatin. In addition, extremely normal pulsation was confirmed not only in the peripheral iliac canal but also at the transplant site.

The surgical site is irrigated with saline and the retroperitoneal space is 3-0
The internal organs were replaced using interrupted sutures using polyglycolic acid. During this surgery, the baboon's respiratory response was normal. The posterior peritoneum and peritoneum of the abdominal wall are continuously
-Seal with a layer of silk and interrupt the anterior peritoneum 2-
It was sealed with a layer of 0 silk. In addition, the epidermis, 3
Continuous sutures were made using -0 nylon thread. The anesthesia used for this surgery was short-lasting neon butal. Although the amount of blood lost during this operation was approximately 50 c.c. to 75 c.c., the baboon tolerated the operation well and remained conscious for 30 minutes.

The day after the surgery, the baboons were sitting and walking in their cages, and three days later, they ate the same food as usual, came out of their cages, roared, climbed walls, and made visible appearances. , was in extremely good health. The baboon's legs were warm and its pulse was normal.

As understood from the above description, various other transplant surgeries can be performed using the graft excised from the umbilical cord according to the present invention. If necessary, the venous artery dissected from the umbilical cord can be dissected longitudinally to create a larger radius graft. In addition, the umbilical cord conduit, or a portion thereof, can be tanned or used as is for the purpose of reinforcing or sealing structural defects in the body, such as the heart, heart valves, or urinary tract. can. Additionally, it can be used to cover epidermal wounds to speed up their healing. It is clear that these various surgeries are within the scope of the technical idea of the present invention.

As can be inferred from FIG. 1, the conduit excised from the umbilical cord 13 is closed at both ends and appears extremely small. In the umbilical cord 13, there are 11 veins.
In this case, the artery is indicated by 12. Venous artery 11,1
2 is covered by WHARTON'S JELLY, as described above, and the artery 12 is twisted and wrapped around the vein 11 and further includes the Hoboken valve.

This condition of the venous arteries 11, 12 has heretofore made it difficult to use them as tubular grafts. Therefore, according to the method according to the invention, the shaft is inserted into the vein 11 and the remnants of the umbilical cord 13 are removed, as described above.

Additionally, the artery 12 is carefully dissected from the umbilical cord 13 and placed on the shaft. Then, after properly tanning the venous arteries 11 and 12, the Hobokin valve is removed, and the shape of the conduit having an inner diameter of less than 1 millimeter is fixed using an appropriate tongue solution. The vein 11 is substantially larger than the artery 12 and can be increased to an internal diameter of up to 1 centimeter by inserting a shaft.

Of course, if such a conduit is cut open and made flat, it can be used as a reinforcing patch for various organs, as a supplement during anastomosis, and even as a graft to cover epidermal wounds.

After the desired conduit is excised from the umbilical cord and any residual blood is washed away, the conduit is cleaned with a sclerosing agent for approximately 3 to 10 minutes. This treatment is effective in removing Hobokin valves within the conduit. The most suitable curing agent is an aldehyde group, for example,
Examples include formaldehyde, glyoxal, dialdehyde starch, and gluteraldehyde.
Among these, gluteraldehyde is most suitable for the purpose of removing antigenicity and thrombogenicity, followed by dialdehyde starch solution. In addition, the concentration of the glutaraldehyde solution is
0.15% to 0.7%, the concentration of the dialdehyde starch solution should be 0.5% to 2.0% by weight. If the concentration of the glutaraldehyde solution is lower than this, it will not be possible to remove the antigenicity of the conduit, and if it is higher than this, the reaction effect will be too rapid and make the walls of the conduit brittle.

After cleaning the conduit with the curing agent as described above, the conduit is placed over an appropriately shaped shaft. It is then soaked in a tank (not shown) containing a curing agent for 15 to 45 minutes. In the meantime, the conduit follows the shape of the shaft inserted into it.
The curing agent is preferably a 0.5% glutaraldehyde solution prepared by buffering the pH of a 1% sodium carbonate solution to 7.5 to 8.5. This hardening agent has the effect of making the shape of the conduit into the shape of a shaft and further strengthening the material forming the conduit.

FIG. 3 shows another embodiment that allows the shape of the conduit to be determined. The vein 11 is inserted into a tubular mold 18 and its end 19 is sealed with a stopper 21.
The other end 22 of the vein 11 is connected to a hose 23 through which the sclerosing agent 16 is injected under appropriate pressure. The wall of the vein 11 is pressed against the inner wall of the mold 18 by the pressure of the hardening agent 16 injected, and a venous tube having a shape corresponding to the inner wall of the mold 18 is formed. This step results in a smoother outer surface of the conduit.

The method of reducing the venous artery using the cylindrical shaft 15 (see FIG. 2) or the tapered shaft 25 (see FIG. 4) allows the removal of irregularities inside the conduit such as the Hobokin valve. There is an advantage. In FIG. 4, reference numeral 24 indicates a conduit placed over the tapered shaft 25. As shown in FIG. The conduit is
It may be either the vein 11 or the artery 12. The small diameter umbilical artery is also particularly suitable for replacing blood vessels within the body. In this case, the umbilical cords of mammals larger than humans have larger ducts, even though the umbilical cords of these mammals are more difficult to obtain than the umbilical cords of humans.
Their use allows for larger and thicker walled graft conduits and patches. In addition, the umbilical cord duct of small mammals is primarily
It can be used as a graft for conduits within the toes of fingers and feet.

It should be noted that when a conduit graft treated according to the method of the invention is applied to a blood vessel with an internal diameter of up to 2 millimeters, there is no need to reinforce the blood vessel with an artificial mesh. That is, smaller diameter conduits generally can withstand higher pressures, and if the interior of the conduit is empty, the thickness of the conduit wall will increase. Furthermore, a harder conduit can be formed by soaking the conduit in alcohol before hardening with an aldehyde.

As mentioned above, after hardening the conduit,
Treat the conduit with a 1% solution of sodium bicarbonate (NaHCO ₃ ) to remove the curing agent. Additionally, it is advisable to treat the conduit for 30 to 40 minutes with a chemical capable of reacting with the remaining aldehyde, such as amino acids, or their alkali salts, or veloxide, peracid, hypochlorite. A dilute oxidizing agent such as Amino acids with sodium salts such as L-sodium glutamate, L-sodium aruninate, L-sodium phenylalaninate, and L-cysteine have antithrombodiene properties and are particularly suitable for this purpose. Incidentally, among the above sodium salts, glutamic acid is most suitable. Furthermore, in a method in which an aldehyde used as a curing agent is removed using an amino acid, the amino group of the amino acid is said to have the function of condensing the carbonyl group of the aldehyde. That is, the carbonyl group condensed by the amino group is freely ionized and transfers a negative charge to the surface of the conduit, and the surface has antithrombodiene properties.

Furthermore, as noted above, the preferred method of preserving the umbilical cord conduit after it has been cured and treated to have a certain shape is to use a dilute solution of aldehyde; Another characteristic feature is that the conduit is then treated with amino acids.

A preferred method for preserving tanned umbilical cord conduits is to use a 0.5% gluteraldehyde solution. It should be noted that the conduit will further harden over a period of 4 to 6 days, but the degree of hardening during the storage period will be extremely small.

After storage, the conduit is cleaned with sterile saline or 1% sodium bicarbonate solution in preparation for transplantation surgery. At this time, it is desirable to treat the conduit once again with sodium L-glutamate to remove aldehyde residues.

Another method of conduit preservation is to preserve the conduit in 40% to 50% aqueous alcohol containing 1% propylene oxide.
% solution. At this time, it is of course not necessary to carry out a treatment to remove aldehydes as in the above-mentioned method.

It goes without saying that many other different ways of treating the umbilical cord conduit described above are possible. In any case, after cleaning the umbilical cord vein, a tapered or straight shaft is inserted into the venous canal, and on a lathe, the frozen umbilical cord cord is removed from the shaft inside the chuck of the lathe. Cut off everything except the venous tube, including the rod, and place it on a lathe. Furthermore, in this process,
By cutting the outside of the venous duct, it is also possible to standardize the wall thickness of the vein. Moreover, it can also be made into a tapered shape as desired. After completing this step, it is necessary to keep the conduit sterile using inertial means such as photoirradiation, antibiotics, high temperature treatments, etc. In the case of high-temperature processing, raising the temperature to around 60°C while tanning the conduit will speed up the tanning process. This method can also be applied to remove tan peel fluid residue.

Furthermore, as shown in FIG. 5, if the venous tube 20 is divided into flat pieces, it can be used as a reinforcing material or a patch for various internal organs. For example, as shown in FIG.
is sutured using suture thread 28, and the suture line 2
If there is 7, paste 2 that divides the umbilical cord duct into flat parts.
9 on the suture line 27 and sutured to the conduit 26, stronger suturing can be achieved.

The function of the umbilical cord conduit as a patch is not just for reinforcement. As is well known, when performing surgery to suture the walls of a certain organ, care must be taken not to pull the sutures too tightly.
Care must be taken that the seams are not too close to each other. Otherwise, the blood supply to the wall of the organ will be cut off, and there is a high risk that gangrene will develop. Therefore, when using normal suturing techniques,
Blood leakage can be seen from the suture line of the wall. It is for this reason that so-called drains are often used. By using the umbilical cord conduit patch according to the present invention, this blood leakage can be prevented to a considerable extent, if not completely.

FIG. 7 shows another embodiment in which the umbilical cord conduit according to the present invention is used as a patch when performing an anastomosis surgery on the intestine 31. Normally, when the intestine is incised, the ends 32 and 33 are bent inward as shown in FIG. Both ends 32 and 33 are connected to a suture thread 34
After the seams are sewn together, a patch 36 according to the present invention is sewn onto the seams at both ends 32 and 33. In this way, intestinal contents can be prevented from leaking into the abdomen. In this example, the patch was applied only once around the intestines, but of course it was applied twice.
It is also possible to do it three times.

Additionally, multiple umbilical cord conduit patches may be used to reinforce the pericardium or heart valves of the heart, or to cover artificial implants such as pacemakers. Furthermore, it can be used as an insertion material that is difficult to deteriorate in orthopedic surgery.

Although the umbilical cord tube that has undergone hardening treatment does not have that much tensile strength, it is free of antigenicity and thrombogenicity, is flexible and slippery, and is used as a guide for various organs in the body. It has the property of being able to bond with both, making it extremely useful during transplant surgery.

As mentioned above, the umbilical cord conduit graft according to the present invention has a very wide range of applications, such as being able to be used for reinforcing seams in suturing surgeries.

In addition to the scope of use described above, it can also be used as an artificial conduit to connect the urinary sac and the epidermis, for example, when reinforcing defective or weak parts of the wall of an organ such as the urinary sac.

Furthermore, the most effective use of the umbilical cord conduit graft according to the present invention is when the graft is used as an eye sling when performing retinal detachment surgery.

In FIG. 8, 47 indicates an eyeball, and 48 indicates a pupil of the eyeball 47. The area operated on using this graft is indicated by 49. In this case, a certain amount of pressure is applied to the surgically performed area 49 until the retina is permanently attached to the eyeball 47 . At this time, if the eyeball holder 51 formed from the umbilical cord conduit is worn around the eyeball 47, the inner surface of the retina will be pressed against the eyeball 47 by its pressure. still,
In this case, it is necessary to increase the pressure on the eyeball 47 to approximately 30 millimeters of mercury.

In the prior art, the eye holder 51 was formed from silicone plastic or pleural lather. The former method damages the eyeball and
It has the disadvantage of transmitting external bacteria, and if the surgery fails, the patient is likely to become completely blind. On the other hand, if a pleura lata is used, an operation is required to obtain the pleura before ophthalmic surgery. However, with the umbilical cord conduit graft according to the present invention, the disadvantages found in the prior art can be overcome, and
It won't hurt your eyeballs.

Another important example in which the umbilical cord conduit graft can be used as a patch is when it is implanted into the epidermis of a burn or wound. This epidermal transplantation can not only be performed on areas infected with skin infectious diseases, but in many cases, after the transplantation,
There is no need to protect the area with a bandage. In other words,
This is because the graft adheres to the skin very quickly. Even if the area where the skin is grafted using the patch is infected with an infectious disease, the treatment progresses extremely quickly. The transplanted patch generally remains attached for 7 to 8 months, but will fall off if treated sufficiently.

As has become clear from the various examples above, there are many advantages to using a human or mammalian umbilical cord. Not only is the supply of umbilical cord completely unlimited, and the method of making its conduit available for transplantation surgery is extremely simple, but its range of applications is truly wide-ranging, and the unlimited supply makes production difficult. The cost is also low. Additionally, these umbilical cord conduits can be permanently stored in a variety of forms and even have a desired thickness. Also, if the umbilical cord conduits are preserved in a dilute glutaraldehyde solution, their actual use requires simply rinsing them with sterile water, saline, or dilute sodium bicarbonate solution. Further, if desired, in order to remove aldehyde residues, it may be further washed with L-sodium glutamate solution.

To tan the umbilical cord ducts and give them a certain shape, mix them with water, sterile saline, Ringer's lactate solution,
Clean with hydrogen peroxide, sodium bicarbonate solution, alcohol, or transplant reflux solution. In addition, drugs for imparting antithrombodyne properties to the graft include L-sodium glutamate, L-alanine, L-phenylalanine, L-cysteine, and L-lysine. These compounds may also be used in removing tan skin fluid residues.

Whalton's gelatin can be removed by dissolving the hyaluronic acid forming the gelatin using a hyaluronic acid degrading enzyme. Furthermore, the same purpose can be achieved using saline.

The shaft that defines the shape of the umbilical cord conduit may be made of glass, silicone plastic, stainless steel, or other material that is inert to the implant and the chemicals used in the process. The shaft rod can be adjusted as desired.
It can be of any shape.

The aldehyde group used as tan peel liquid contains
These include glutaraldehyde, dialdehyde starch, formaldehyde, absolute alcohol, glyoxal, or chromic acid.

In addition to amino acids, mild oxidizing agents such as diluted hypochlorite solution and diluted peroxide are also effective in removing aldehyde residues in tanning solutions.

Furthermore, in the case of conduit grafts having an inner diameter of 5 millimeters or more, the exterior of the conduit is generally covered and reinforced with a mesh-like support member. Such reinforcing support members include polyester and fluorocarbon-plastic, with polyester being preferred. A commercially available mesh support member (Marcillin) has a mesh spacing of 0.5 to 2 millimeters, and is wrapped around the conduit to provide additional force and support to the graft, and is itself not part of the graft. It is buried in. This support member is preferably a pre-formed cylindrical support member.

An implant reinforced with such a support member is tested for its strength, the presence of leakage, by means of a vibrator and by forcing a solution into the implant under a pressure of 150 to 300 millimeters of mercury.

It will be understood that by using the method detailed above, the object of the invention stated at the beginning can be fully achieved. Further, various other modifications can be made without departing from the technical idea and scope of the present invention, and the advantages and features of the present invention are not limited to the embodiments described in detail above.

Embodiments of the present invention are listed below.

(1) An umbilical cord conduit transplant, which is a graft excised from a mammalian umbilical cord conduit and used as an artificial tube, wherein the graft is non-antigenic and non-thrombodigenic. Piece.

(2) The umbilical cord conduit graft according to item 1, wherein the umbilical cord conduit used as the prosthesis is located within the umbilical cord.

(3) The umbilical cord conduit graft according to item 1 above, wherein the graft can have a shape and hardness depending on an appropriate purpose.

(4) The umbilical cord conduit graft according to item 1 above, wherein the graft has a cylindrical shape and the outer periphery thereof is reinforced with a flexible and plastic mesh member.

(5) A method for producing an umbilical cord conduit graft to be used as a prosthesis, comprising: (a) removing at least one major blood vessel of the umbilical cord; and (b) subjecting said blood vessel to a hardening treatment with a reagent. A method for manufacturing an umbilical cord conduit graft, further comprising the step of: (c) imparting an appropriate shape to the blood vessel.

(6) The method for producing an umbilical cord graft according to item 5, wherein the graft is hardened with any one of gluteraldehyde, formaldehyde, dialdehyde starch, and glyoxal.

(7) The umbilical cord conduit graft according to item 5, wherein the graft is hardened with a glutaraldehyde solution having a concentration of 0.15% to 0.6% for a period of 15 minutes to 45 minutes. Production method.

(8) washing the aldehyde-treated graft with water, saline, and diluted sodium bicarbonate;
The seventh method further comprises the step of removing residual aldehyde from the graft using any one of an amino acid, an alkali salt of an amino acid, an amine, a hydroxylamine peracide, a peroxide, or a hypochlorite. The method described in section.

(9) The method according to item 5, further comprising the step of preserving the graft in a sterile sealed container.

(10) repair or augment any duct or organ in the body;
or replacement method, characterized in that a portion of the umbilical tube is sewn into or secured in place of the interior or top of the wall of the body conduit or organ.

(11) The method according to item 10, wherein the umbilical cord portion is solidified and shaped. (12) The graft has a tubular shape and the graft surface is reinforced in a mesh shape. The method according to item 10 above, characterized in that

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the umbilical cord, and FIG. 2 is a partial cross-sectional view of the umbilical cord conduit covered on a cylindrical shaft.
FIG. 3 is a partial sectional view of the umbilical cord conduit pressed against the inner surface of the mold, FIG. 4 is a partial sectional view of the umbilical cord conduit covered on the tapered shaft, and FIG. A perspective view of the patch formed by incising the umbilical cord conduit, FIG. 6 is a side view showing a state in which the suture line of the conduit is reinforced with the patch, and FIG. 7 is an anastomosis using the plate-shaped patch. FIG. 8 is a partial cross-sectional view of the conduit in a reinforced state, and FIG. 8 is a perspective view showing a state in which the eyeball holder is pressing against the retina of the eyeball. 11 is a vein, 12 is an artery, 13 is an umbilical cord, 15 is a shaft rod, 16 is a hardening agent, 18 is a mold (mold), 1
9 is an end, 20 is a flat vein, 21 is a stopper, 22 is the other end, 23 is a hose, 24 and 26 are conduits, 25 is a shaft rod, 27 is a suture line, 28 is a suture thread,
29 is the patch, 31 is the intestine, 32 and 33 are the ends, 36
37 is an eyeball, 48 is a pupil, 49 is a surgical range, and 51 is an eyeball holder.

Claims (1)

[Claims] 1. Flexible grafts excised from mammalian umbilical cord ducts and used as artificial organs in mammals, i.e., for reinforcing and repairing body duct systems, body tissues, body organs, grafts, and coverings. A flexible umbilical cord conduit graft used in the form of a patch, characterized in that the umbilical cord conduit graft is non-antigenic and non-thromposinic. .