Transplantation of tissues: procedure, forecast

Skin allografts are used in patients with extensive burns and other conditions with massive loss of skin. Allografts are used to cover large affected surfaces and, thus, reduce the loss of tissue fluid and proteins and prevent the development of invasive infections. All allografts eventually must be rejected, but well-vascularized granulations are formed on the exposed surfaces, on which autografts from the healed areas of the patient's skin are well established. Skin cells can be grown in culture, then returned to the burned patient to cover the surface of extensive burns; artificial skin created from a cell culture on a synthetic substrate can also be used. Split skin graft is used to accelerate the healing of small wounds. A small piece of tissue several millimeters thick is treated in a special way, and the donor skin is located at the transplant site.

Cartilage transplantation is used in children with congenital defects of the nose or ears and in adults with severe lesions or joint destruction (for example, severe osteoarthritis). Chondrocytes are more resistant to rejection, perhaps because a small number of cells in the hyaline cartilage are protected from attack by the cells of the immune system with a cartilage matrix.

Bone transplantation is used to reconstruct significant bone defects (for example, after massive resection for bone tumors). Viable donor bone cells do not survive in the recipient, but the dead matrix of the allograft can stimulate the recipient's osteoblasts to recolonize the matrix and form a new bone. Matrix plays the role of the basis for connecting and stabilizing defects until a new bone is formed. Cadaver allografts are frozen to reduce the immunogenicity of the bone (which dies by the time of implantation) and glycerolysis to maintain the viability of the chondrocytes. No immunosuppressive therapy after implantation is used. Although anti-HLA antibodies are formed in patients, early observations do not reveal cartilage degradation.

Autografts of adrenal medulla are stereotaxically located within the CNS, which facilitates, according to publications, the symptoms of Parkinson's disease. It is also suggested to use allografts of adrenal tissue, especially from donor-fruit. It is reported that fetal tissue of the ventral midbrain (mesencephalon) is stereotactically implanted in putamen (the shell is the lateral part of the lenticular nucleus of the terminal brain) of patients with Parkinson's disease to reduce rigidity and bradykinesia. However, in connection with the ethical and political debate regarding the possibility of using human fetal tissues to conduct a sufficiently large number of controlled trials to adequately assess the transplantation of fetal neural tissues, it seems unlikely. Currently, xenografts of endocrinologically active cells are tested from donors-pigs.

Implants of fetus thymus, obtained from stillborn children, can restore immunological reactivity in children with thymic aplasia and the consequences of abnormal development of the lymphoid system. Since recipients are immunologically inactive, immunosuppressive therapy is not required, but the development of a serious "graft versus host disease" is possible.