Introduction:The term photoaging describes the sun damaging effects on skin mainly due to chronic ultraviolet (UV) light exposure. The unsatisfactory results of the available anti-aging strategies raise the demand for alternative forms of treatments. Adipose-derived stem cells (ASCs) are available in abundant quantities, harvested by a minimally invasive procedure, safely transplanted and differentiated along multiple cell lineages. Subsequently, used in treatment of many diseases. Aim: To assess the potential ability of ASCs to ameliorate skin changes induced by chronic exposure to artificial light source similar to the sun rays in its UVA and UVB spectrum in adult female guinea pigs. Material and Methods: Adipose-derived stem cells were isolated from subcutaneous white adipose tissue of five adult human donors undergoing elective liposuction surgery. Twenty adult female guinea pigs were used and were randomly divided into two groups each was subdivided into two subgroups "five animals, each". Subgroup IA served as the control group. Subgroup IB was intradermally injected with phosphate buffered saline solution. Subgroup IIA served as the photoaging model. Subgroup IIB served as the photoaging model intradermaly injected with ASCs. Isolated stem cells were cultured and characterized. Skin specimens were prepared and examined using different histological and immunohistochemical techniques. Morphometric and statistical studies were also performed. Results: Subgroup IIA showed various UV damaging effects in the skin epidermis and dermis, while ASCs injection in subgroup IIB resulted in partial restoration of the skin structure. Conclusion: Intradermal injection of ASCs partially ameliorated the photo-damaging effects. Further studies are needed before ASCs clinical application.

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Background Skeletal muscle injuries are frequently encountered in athletes and military personnel. Incomplete functional recovery of these injuries usually occurs due to fibrosis of the skeletal muscle. Recently, oral administration of losartan antihypertensive drug was claimed to have a role in improving skeletal muscle healing, but still to be furtherly investigated. Aim of the work This work aimed to assess the healing effect of losartan on the histological structure of induced lacerated skeletal muscle fibers of adult male albino rats. Material and Methods Forty male albino rats were used in this study. They were divided into three groups: Group I: served as a control group and included 15 adult rats. Group II (muscle laceration group): consisted of 15 rats that were subjected to muscle laceration injury. They were subdivided into subgroup IIa: consisted of five rats that were sacrificed one day after injury, subgroup IIb: it included 10 rats that were left for spontaneous recovery for two weeks after injury. Group III (losartan-treated group): it consisted of 10 rats that were subjected to muscle laceration injury then they received oral losartan from day three till end of experiment. All rats, except rats of subgroup IIa, were sacrificed two weeks after injury. Right gastrocnemius muscle specimens were taken and processed for light microscopic examination by H & E and Masson's trichome stains as well as morphometric and statistical analysis. Results In group II, there was almost complete affection of myofibers at site of injury after 1 day of induced laceration in the form of myofibers fragmentation, disorganization and distortion with apparent mononuclear cellular infiltration mainly neutrophils and macrophages. After 2 weeks some myofibers were seen distorted and ended abruptly into connective tissue, others were branched with unclear striations. Mononuclear cellular infiltration between myofibers and apparent dilated blood vessels at laceration site were also noticed. A significant increase in collagen fibers deposition between regenerating muscle fibers (p<0.05) was also demonstrated. Treatment of the muscle laceration by losartan in group III showed apparent partial improvement in the form of significant decrease in collagen fibers deposition (p<0.05) and apparent decrease in mononuclear cellular infiltration as compared to that of group II. Also, some of the regenerated myotubes were noticed with chains of central nuclei. Conclusion Excess collagen fibers deposition between myofibers hinders regular arrangement of generating myotubes. Losartan might enhance muscle regeneration through decreasing collagen fibers deposition. However, it needs longer duration to assure complete muscle healing.