Joris van Dongen

332 Chapter 14 The lackof skinqualityimprovement inageing facial skinmight be causedbytheabsence of a ‘trigger’ to stimulate adipose tissue or tSVF to regenerate damaged tissue. Aging of the skin is a physiological process of a gradual decrease of elasticity, primarily caused by reduced elastin deposition in the extracellular matrix by skin fibroblasts. This can be due to hormonal changes, genetic factors aswell as environmental influence e.g. cigarette smoke and ultraviolet radiation. 28 Our hypothesis is that ‘ordinary’ aging of the skin is a normal physiological process in which certain components of the extracellular matrix, such as elastin gradually disappears. In other aspects, such as epidermal regeneration, perfusion, and neurosensation, no markable changes occur due to ageing. Hence, tSVF has little to repair. Moreover, de novo generation of dermal elastin is often considered absent or inefficient whilst this would neither lead to tightening of the expanded aged tissue. In this way, ageing-related skin changes are not considered damaged tissue and do not result in clinically identifiable changes of the skin as a result of facial lipofilling. In literature, only two studies have reported histological improvement of facial skin after autologous lipofilling enriched with tSVF, adipose derived stromal cells (ASCs) or PRP. 21,22 Three months after injection, the reticular dermis showed a decrease and more dissociated fiber network containing smaller as well as smoother fibers in comparison with before injection. Moreover, in the ASC as well as tSVF enriched lipofilling group a higher number of superficial oxytalan elastic fibers in the papillary dermis were noted. Skin consist of a complex organization of three types of elastic fibers: oxytalan, eluinin and elastic fibers. 29 Oxytalan fibers are immature elastic fibers containing mainly microfibrils devoted of elastin crosslinking, while the extent of elastin crosslinking increases in elauinin and elastic elastic fibes. This indicates that the three types of elastic fibers represent different stages of elastogenesis of the skin. 30 A larger amount of oxytalan elastic fibers might indicate elastogenesis. However, changes in eluinin and elastic elastic fibers were not mentioned. 21,22 Another histological study demonstrated an increase in dermal thickness after lipofilling in comparison with no treatment after 69 days. 23 Yet, all studies lack a control group with microneedling only. It is well-known that needling of the skin results in histological changes of the skin including finer and more organized dermal elastic fibers. For this reason, histological improvement after autologous lipofilling might be a needling effect. In this case, microneedling alone would be sufficient to improve skin quality and thus autologous lipofilling unnecessary. Furthermore, no clinical effects were measured while histological improvement might not always be clinically significant. Compared to physiological ageing of the skin, pathophysiological processes e.g. dermal fibrosis or chronic wounds might be accelerated by tSVF. Pathological processes go along with a disbalance of extracellular factors resulting in inflammation, excessive extracellular matrix deposition and crosslinking, or a lack of angiogenesis. Lipografting