Mesenchymal stem cells (MSCs) are multipotent stem cells derived from adult stem cells. Primary MSCs can be obtained from diverse sources, including bone marrow, adipose tissue, and umbilical cord blood. Recently, MSCs have been recognized as therapeutic agents for skin regeneration and rejuvenation. The skin can be damaged by wounds, caused by cutting or breaking of the tissue, and burns. Moreover, skin aging is a process that occurs naturally but can be worsened by environmental pollution, exposure to ultraviolet radiation, alcohol consumption, tobacco use, and undernourishment. MSCs have healing capacities that can be applied in damaged and aged skin. In skin regeneration, MSCs increase cell proliferation and neovascularization, and decrease inflammation in skin injury lesions. In skin rejuvenation, MSCs lead to production of collagen and elastic fibers, inhibition of metalloproteinase activation, and promote protection from ultraviolet radiation-induced senescence. In this review, we focus on how MSCs and MSC-derived molecules improve diseased and aged skin. Additionally, we emphasize that induced pluripotent stem cell (iPSC)-derived MSCs are potentially advanced MSCs, which are suitable for cell therapy.

Although the study of lakes has traditionally focused on pelagic production pathways, recent stable isotope and diet evidence indicates that benthic algal production is an important contributor to fish production. This has led to the suggestion that energy may be more efficiently passed along benthic food chains relative to their pelagic counterparts. To test this idea, we combined stable isotope based assessments of energy flow pathways with estimates of pelagic- and benthic-based primary and secondary production in Castle Lake, California. Approximately 50% of whole-lake primary production and 30% of whole-lake secondary production occurred in benthic habitats. Stable carbon isotopes and dietary data indicated that fish were predominantly supported by benthic (63%) and terrestrial (24%) secondary production. Ecological efficiencies (algal production / invertebrate production) were low in Castle Lake (<3%), though zoobenthic production was more efficiently passed to fish than was zooplankton production. The larger size of benthic prey relative to pelagic prey may affect fish prey selection and foraging efficiency, resulting in differences in ecological efficiency between pelagic and benthic trophic pathways.