The Possible Therapeutic Effect of Adipose Derived Mesenchymal Stem Cells` Exosomes versus Topically Applied Growth Factors on photoaged Skin in adult male Albino rat. A Histological study

Background: Exosomes have various effects on the skin after exposure to ultraviolet (UV) rays. Growth factors are natural proteins that promote tissue growth and organization.Aim: investigate the possible therapeutic effect of exosomes from adipose mesenchymal stem cells (ADSC) versus topically applied growth factors on the histological structure of photoaged rat skin. Material: 45 young adult male rats were used. 10 rats were used for preparation of ADMSCs and isolation of exosomes. 35 were classified into 4 groups: Group (I): Control group 20 rats, Group (II) 5 rats: shaved back skin was exposed to UVA + UVB irradiation, for two weeks (5 days / week) and were left untreated for further one week then were sacrificed. Group (III) 5 rats: after UV exposure as in group II, rats were injected with one dose of purified exosome concentrate (300µg/rat) subcutaneously, then were sacrificed one week later. Group IV 5 rats, after UV exposure as in group II, rats were given topical growth factors gel (2ml) after micro-needling procedure for 3 times in 30 days (once every 10 days), then sacrificed one day later. Skin specimens were collected and subjected to histological studies. Morphometry and statistics were performed. Results: group II showed vacuolated keratinocytes with pyknotic nuclei, indistinct dermo-epidermal junction, Rarified and disorganized hair follicles. Also, a decrease in mean epidermal thickness, CD-31 and collagen fibers were found with increase in mean count of KI-67. Groups III & IV revealed a significant amelioration of the altered microscopic photoaging changes. Conclusion: When rats' skin was exposed to UV radiation, noticeable structural alterations occurred. Growth factors and exosomes significantly reduced the photoaging changes in the skin. Compared to exosomes, this effect was more noticeable when growth factors were administered topically.Keywords: skin aging, Ultraviolet, growth factors, exosomes, KI-67, CD-31.