BONE GRAFTS FOR RECONSTRUCTION OF BONE DEFECTS (REVIEW).

Reconstruction of large size defects of bone is a challenging task. To this date, discussions and controversies on selection of auto-, allo-, xeno- or synthetic grafts continue to take place. Vascularized autologous bone graft is considered as gold standard in reconstruction of large size defects of bone; however an additional surgery is required for obtaining it. Allografts and xenografts possess osteoconductive features, but osteogenesis is less expressed and risk of various infection transmissions is high and may have probability of developing immunological conflict. Main advantages of grafts created from synthetic materials through bioengineering methods are biocompatibility and good bioreabsorption. Despite these features, studies related to the creation of an ideal bone graft continue to take place that should have biomechanical stability, be able to degrade within an appropriate period, exhibit osteoconductive, osteogenic and osteoinductive properties. Nowadays, there is an attempt of creating grafts that contain platelet-rich plasma, growth factors or stem cells for strengthening osteoconduction and osteoinduction of bone grafts. In 2016, we created bioactive bone from decellularized bovine femoral bone and freeze-dried bone marrow stem cell paracrine factors. We hypothesized that freeze-dried BMSC paracrine factors would have ability to strengthen osteoinduction, osteoconduction and osteointegration. Experimental and preliminary clinical investigations indicated that bioactive bone grafts containing freeze-dried BMSC paracrine factors may be used for reconstruction of large size bone defects. Despite acquired positive results, it requires multiple experimental and clinical studies for further improvement of graft.

CURRENT CONDITION AND CHALLENGES IN TREATMENT OF NON-HEALING WOUND AFTER RADIATION THERAPY (REVIEW).

Radiotherapy is a common cancer treatment, but often together with tumor cells, the surrounding normal tissues are damaged as well, which leads to the complications such as skin atrophy, soft tissue fibrosis, desquamation, epithelial ulceration which leads to poor healing of wounds. In this review, our main attention will be paid to the treatment of non-healing wound after radiation therapy. Irradiated wounds are often resistant to conventional treatment modalities and may often require surgical reconstructive intervention. The reconstructive options usually include skin grafts, local and regional flaps. Local flaps may be unreliable, since in some of the cases they are affected by irradiation. However, the complication rate with regional flaps is just as high as that with local flaps, and is not significantly different when analyzed according to the type of reconstructive procedure performed. In addition, such wounds affect not only the physical, but also the mental health of patients and their productivity. Therefore, non-healing wounds represent a significant problem for patients and remain a major challenge in modern medicine. Recently, for the healing of non-healing wound, several novel approaches have been proposed such as using the bone marrow stem cells (BMSC), biologically active dressings, bioengineered skin equivalents and others. Of special interest are bioactive membrane consisting of decellularized human amniotic membrane and BMSC paracrine factors, which may be effectively used for the treatment of non-healing wounds that have developed following the radiotherapy. Despite the positive results achieved in a number of cases, it is early to state that the all of the above methods is an ideal for the treatment of non-healing wounds, since it requires additional experimental and clinical studies for ascertaining positive and negative features.