TRANSPLANT

From Big Medical Encyclopedia

(Latin of transplantare to replace the TRANSPLANT) — the site of fabric or body used for transplantation.

According to classification of specific differences of T., offered at the beginning of the 60th by a number of researchers, distinguish: autotrans

plantat (the outdated term «autologous transplant») during the use for change of own bodies or body tissues; isotransplant at organ transplantation or the fabrics taken from organisms, genetically completely or more identical; allotransplant (the outdated term «homologous transplant») at organ transplantation or fabrics from an organism of the same look; heterograft (the outdated term «hetero-logical transplant») at organ transplantation or fabrics from an organism of other look. The allotransplant which got accustomed in an organism of the recipient and keeping viability call allovitalny, or gomovitalny. When allotransplant, napr, bone, serves only as a framework for germination of again formed tissue of the recipient, it call allostatic.

Most often use T. skin, muscles, sinews, bone, cartilaginous and fatty fabrics, vessels, nerves, cornea, marrow. To organ T. the kidney taken from close relatives of the recipient or from a corpse is. At the same time it is important to type T. in relation to the recipient, considering features of transplant immunity and immunol. incompatibility of fabrics (see Immunity transplant, Incompatibility immunological) and also to establish

T. V viability a crust, time by the most objective indicators of viability of T. are fiziol., biochemical and morfol. criteria of its functional activity. E.g., important criterion of a functional state and viability renal T. duration of his ischemia is (duration of the period from the moment of death of the donor to revascularization of T. in an organism of the recipient). When duration of ischemia renal T. exceeds 40 — 60 min., as a rule, its function is broken. To increase duration of reversible ischemia of T. it is possible by means of methods of conservation of bodies and fabrics (see).

On a functional condition of T. also duration of the agonal period of the donor since in process of increase in this period ischemic changes in all bodies accrue has significant effect (see the Agony). For assessment of extent of these disturbances measure the perfused pressure, i.e. size of minimal pressure, at Krom there is a perfusion (see) a transplant, and also duration of this process and amount (in unit of time) of the preserving solution necessary for liberation of body from blood. The importance is attached also to the size of resistance of a vascular bed and an arteriovenous difference on oxygen characterizing respiratory activity of body, utilization of oxygen by it, etc. Functional capacity renal T. estimate on time of the beginning of urination, and also amount of the emitted urine during the first hours after transplantation (see Renal transplantation). Among the biochemical indicators allowing to estimate degree of functional safety of cadaveric tinned kidneys and a liver, the most reliable — coefficient of oxidizing phosphorylation (see biological oxidation). Importance in assessment of viability of T. get emergency morfol. and gistokhy. researches of the material received by means of a puncture biopsy.

Morfol. changes in transplanted organs and fabrics consist of a complex of disturbances. The ratio, character and expressiveness of immune disturbances in many respects depend on degree of a tissue incompatibility, a type of a transplanted organ or fabric, quality and conditions of their preservation, on a look and weight of operation, localization of T. in an organism of the recipient, a look and duration of immunodepressive therapy (see the Immunotherapy), duration of stay of T. in an organism of the recipient.

The transplanted organ in the 1st days is increased in volume, is full-blooded. Morphologically in it find signs of an acute disorder of microcirculation (see), hypostasis of a perivasku-lyarnoa and interstitial fabric, hemorrhage, decrease of the activity of oxidation-reduction enzymes and increase in activity of hydrolases in parenchymatous cells, the necrobiotic changes and other structural disturbances caused by ischemia of T., come during preparation for transplantation, disturbance of a limfootton and denervation. Considerably these changes can be caused by the processes developing in the agonal period at the donor if T. it is taken from a corpse. Morfol. symptoms of ischemia, disturbance of a lymphokinesis and denervation come to light at once after recovery in T. blood circulations. Venous stagnation, heart attacks of T. or his death there can occur also owing to thrombosis of a vascular anastomosis, changes of rheological properties of blood of the recipient, discrepancy of a blood-groove in T. and vessels of the recipient, with to-rymi anastomozirovan a transplanted organ. Especially brightly it is shown at renal transplantation with a double renal artery (see Kidneys, malformations) though existence of such anomaly does not affect function of body in an organism of the donor.

At autotransplantation early structural disturbances are, as a rule, insignificant and are in most cases reversible. At hallo - and xenotransplantations morfol. signs of a tissue incompatibility are shown in the form of small perivascular infiltrates from lymphocytes, histiocytes, pironi-nofilny cells of a plasmatic row (see Plasmocytes) and undifferentiated a mononuklea-ditch with large kernels (the end of the 1st week). In the middle of reaction (crisis) of rejection infiltrate spreads to walls of blood vessels and interstitial fabric of all T. V this period in infiltrates mononuclear pironi-nofilny cells prevail, and in a large number plasmocytes and fibroblasts appear later. In mature mononukleara by means of an immunofluorescence (the SI.) it is possible to reveal immunoglobulins. During the same period the fibrinoid necrosis of walls and fibrinferments of blood vessels, expansion limf is observed, vessels, multiple hemorrhages, necrobiotic and dystrophic changes of T. V of a late stage of reaction of rejection in infiltrates develop segmentoyaderny leukocytes. The nature of cellular reaction in many respects depends on weight and intensity of reaction of rejection. E.g., at superacute crisis of rejection into the forefront the phenomena of an acute disorder krovo-act and lymphokineses, and cellular reaction is absent. In the conditions of effective immunodepressive therapy lim-fogistiotsitarny infiltration in T. and in immunocompetent bodies of the recipient it is expressed much more weakly, and terms of her development are extended. At the come engraftment of T. in late terms after change moderate mo-nonuklearny infiltration, sclerous changes of interstitial fabric and walls of blood vessels are observed. Than the period hron is more long. rejection, signs of a sclerosis (see) with substitution of the died parenchymatous elements connecting fabric and the corresponding secondary nonspecific structural changes are more expressed to those. Nek-ry researchers consider the reason of a sclerosis in these cases ischemia, blockade of a lymph drainage and denervation of body since recovery limf, ways and nervous bonds of T. happens to the corresponding systems of the recipient slowly. In disturbance of a trophicity (see) and development of a sclerosis of T., connected with hron. immune process, an important role is played by prolonged use of glucocorticoids as immunodepressive substances (see). Their use for the purpose of an immunotherapy can lead also to an atrophy of cortical substance of adrenal glands, to formation of acute ulcers went. - kish. path, to oppression of a hemopoiesis, etc.

Morfol. changes of allotransplant at repeated change (reimplantation) are characterized by moderate immunocellular infiltration and at the same time more expressed manifestations of disturbance krovo-and lymphokineses.

Except an immune response, effect of immunodepressive substances and factors, and also other reasons of not immune character on morfol. picture T. also diseases of the recipient can influence. E.g., distribution on vessels of T is possible. atherosclerotic process, innidiation in T. tumors and development in it tubercular process at activation of primary centers of this infection in an organism of the recipient under the influence of an immunotherapy, development of a secondary hymenoid glomerulonephritis (see) in the replaced kidney at the recipient with a diabetic nephropathy (see a diabetes mellitus), etc.

Unlike organ fabric T. test oxygen insufficiency after change until blood vessels from adjacent tissues of the recipient do not grow into them. In this regard morfol. symptoms of ischemia and the related trophic disturbances in these cases are expressed longer time. However revascularization of T. does not recover completely viability of the replaced fabric, and only slows down development in it atrophic changes with simultaneous substitution of T. tissues of the recipient.

In the first days after change of an autograft of skin epidermis is in a condition of experience. For 5 — 7 days it looks thinned due to nekrobpotichesky changes of epithelial cells, disturbance of an anizomorfizm of layers, lack of a kera-togialinovy layer. At the edges of T. death of epidermis and infiltration is observed by neutrophilic leukocytes. Small infiltrates from neutrophilic leukocytes are found in a subepithelial layer of a derma and in the central part of the replaced skin rag. More rough changes are noted in a derma — sharp hypostasis, dystrophy of fibers and connective tissue cells, an atrophy of appendages of skin. At the beginning of the 2nd week there occurs proliferation of epithelial cells and gradual recovery of epidermis, except for a papillary layer, to-ry is, as a rule, smoothed. The derma is gradually replaced with the granulyatsionny fabric expanding from tissues of the recipient. Engraftment of an autograft comes to the end with formation on site of a derma of connecting fabric, free of skin of appendages.

At allotransplantation in the 1st days of T. macro - and microscopically looks as well as an autograft. However in it hypostasis, and in the central part of a rag — necrobiotic changes of an epithelium, amotio of a corneous layer of epidermis, death and a growth an eppteliya at the edges is stronger expressed. According to other data, epidermis of allotransplant can be more safe in the beginning that is connected with temporary stimulation of growth of an epithelium antibodies if their concentration does not reach the level necessary for development of destructive processes. From 2nd week after change the progressing death of epidermis and the derma with intensive infiltration of the last leukocytes which further are replaced by lymphocytes, a small amount of plasmocytes is noted. By the beginning of the 3rd week there comes full replacement of T. granulyatsionny fabric, the epithelial cover is formed due to proliferation and increase of epidermis of the recipient.

In allotransplant of a compact bone there is a gradual death of osteocytes, osteoblasts, a rassasyvaniye of intercellular substance and substitution by his again formed bone at the expense of an osteogene cambium of a bone of the recipient (see. Bone plastics). The cellular immune

response at the same time is expressed poorly. By the end of the 1st week around T. proliferation of connective tissue cells with their differentiation in osteoblasts and education bone balochek is noticeable. Later expansion of channels of osteons and germination in them cellular and fibrous fabric with vessels is noted. In 1 — 11/2 month the replaced bone from a surface resolves. In expanded channels of osteons proliferation of cells of an endosteum is observed, signs of bone formation appear. In 2 — 3 months border of T. and bones of the recipient smooth out due to formation of a mature bone callosity.

Unlike bone T., auto-and allotransplants of a cartilage keep the structure. Only in a subperi-hondralny layer the new growth of cartilaginous tissue is noted.

Reorganization of the replaced blood vessels and nek-ry other fabrics is similarly carried out.

See also Transplantation, Transplantation of marrow, Transplantology.

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V. I. Shumakov, A. E. Ivanov.

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