**7. Conclusion**

The basic indication for solid organ transplantation is the treatment of end-stage diseases posing threat to life. Solid- organ transplantation evolved to be gold standard therapy and became a routine procedure with minimal morbidity and mortality figures. Despite the achievements in different fields of transplantation activities, the gap between demand and supply is growing due to an increased percentage of the elderly population, and the increase in the number patients that require organ transplant from which considerable number are lost while awaiting a suitable organ. The unmatched shortage of organs and life-long dependency on immunosuppressive drugs and related complications of immunosuppression had warranted the development of alternative novel technologies for the repair or replacement of missing or malfunctioning organs.

Reproductive, functional, restorative, and psychologic indications have caused the emerging of transplanting different organs, namely face, extremity, and uterus. It is apparent that transplant procedures of these organs will be performed with increasing frequency in the future because successful results are closely associated with the accumulation of useful scientific data and experience.

The unmet demand for organs and the failure of immunosuppressive drugs to prolong long-term graft survival and a variety of complications associated with immunosuppression have caused the need for completely new therapeutic modalities in the treatment of diseased and malfunctioning organs.

For the time being, human grafts and artificial devices are not capable of performing all the functions of vital organs. Artificial devices are beneficial in bridging patients to transplantation, or organ regeneration or as independent implantable units. The ultimate goal is to obtain human grafts to be totally

restored in all their structural and functional aspects, and artificial devices that can completely replace native organs. The hurdles on the way can be overcome by close cooperation and integration of a wide variety of disciplines and technologies including tissue engineering, regenerative medicine, electronics, robotics, artificial intelligence, machine learning, 3D bioartificial printing, bioreactor technology, nano- technology, gene therapy, machine perfusion and cell biology. In light of the recent scientific developments, it can easily be assumed that reaching the goals mentioned is a matter of time. Tissue-engineered products and any kind of device expected to substitute totally human organs must certainly be safe, long durable, and non-immune. The cost-effectiveness and the ease of accessibility are issues to be managed in the future.
