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Abstract-With an increasing incidence of obesity worldwide, rational strategies are needed to control adipogenesis.Growth of any tissue requires the formation of a functional and mature vasculature. To gain mechanistic insight into the link between active adipogenesis and angiogenesis, we developed a model to visualize noninvasively and in real time both angiogenesis and adipogenesis using intravital microscopy. Implanted murine preadipocytes induced vigorous angiogenesis and formed fat pads in a mouse dorsal skin-fold chamber. The newly formed vessels subsequently remodeled into a mature network consisting of arterioles, capillaries, and venules, whereas the preadipocytes differentiated into adipocytes as confirmed by increased aP2 expression. Inhibition of adipocyte differentiation by transfection of preadipocytes with a peroxisome proliferator-activated receptor ␥ dominant-negative construct not only abrogated fat tissue formation but also reduced angiogenesis. Surprisingly, inhibition of angiogenesis by vascular endothelial growth factor receptor-2 (VEGFR2) blocking antibody not only reduced angiogenesis and tissue growth but also inhibited preadipocyte differentiation. We found that part of this inhibition stems from the paracrine interaction between endothelial cells and preadipocytes and that VEGF-VEGFR2 signaling in endothelial cells, but not preadipocytes, mediates this process. These findings reveal a reciprocal regulation of adipogenesis and angiogenesis, and suggest that blockade of VEGF signaling can inhibit in vivo adipose tissue formation.

AFR greatly facilitates topical MAL-induced porphyrins and the fraction of photobleached porphyrins is similar for superficial and deep skin. These observations are consistent with AFR-enhanced uptake of MAL, increased porphyrin synthesis, and photodynamic activation of deep porphyrins even at the lower fluence of 37 J/cm(2), widely used in clinical practice. AFR appears to be a clinically practical means for improving PDT deep into the skin. Clinical studies are suggested to evaluate selectivity in targeting dysplastic cell types.

Background and ObjectivesPretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth of intradermal laser channels and incubation time may affect AFXL‐assisted delivery of methyl aminolevulinate (MAL).Materials and MethodsYorkshire swine were treated with CO2 AFXL at energy levels of 37, 190, and 380 mJ/laser channel and subsequent application of MAL cream (Metvix®) for 30, 60, 120, and 180 minutes incubation time. Fluorescence photography and fluorescence microscopy quantified MAL‐induced porphyrin fluorescence (PpIX) at the skin surface and at five specific skin depths (120, 500, 1,000, 1,500, and 1,800 µm).ResultsLaser channels penetrated into superficial (∼300 µm), mid (∼1,400 µm), and deep dermis/upper subcutaneous fat layer (∼2,100 µm). Similar fluorescence intensities were induced at the skin surface and throughout skin layers independent of laser channel depth (180 minutes; P < 0.19). AFXL accelerated PpIX fluorescence from skin surface to deep dermis. After laser exposure and 60 minutes MAL incubation, surface fluorescence was significantly higher compared to intact, not laser‐exposed skin at 180 minutes (AFXL‐MAL 60 minutes vs. MAL 180 minutes, 69.16 a.u. vs. 23.49 a.u.; P < 0.01). Through all skin layers (120–1,800 µm), laser exposure and 120 minutes MAL incubation induced significantly higher fluorescence intensities in HF and dermis than non‐laser exposed sites at 180 minutes (1,800 µm, AFXL‐MAL 120 minutes vs. MAL 180 minutes, HF 14.76 a.u. vs. 6.69 a.u. and dermis 6.98 a.u. vs. 5.87 a.u.; P < 0.01).ConclusionsAFXL pretreatment accelerates PpIX accumulation, but intradermal depth of laser channels does not affect porphyrin accumulation. Further studies are required to examine these findings in clinical trials. Lasers Surg. Med. 44: 787–795, 2012. © 2012 Wiley Periodicals, Inc.

BackgroundWe investigated if new vessel formation in fat involves the contribution of local tissue-derived endothelial cells (i.e., angiogenesis) or bone marrow-derived cells (BMDCs, i.e. vasculogenesis) and if antiangiogenic treatment by blockade of vascular endothelial growth factor (VEGF) receptors can prevent diet-induced obesity (DIO).Methodology/Principal FindingsWe performed restorative bone marrow transplantation into wild-type mice using transgenic mice expressing green fluorescent protein (GFP) constitutively (driven by β-actin promoter) or selectively in endothelial cells (under Tie2 promoter activation) as donors. The presence of donor BMDCs in recipient mice was investigated in fat tissue vessels after DIO using in vivo and ex vivo fluorescence microscopy. We investigated the roles of VEGF receptors 1 and 2 (VEGFR1/VEGFR2) by inducing DIO in mice and treating them with blocking monoclonal antibodies. We found only marginal (less than 1%) incorporation of BMDCs in fat vessels during DIO. When angiogenesis was inhibited by blocking VEGFR2 in mice with DIO, treated mice had significantly lower body weights than control animals. In contrast, blocking VEGFR1 had no discernable effect on the weight gain during DIO.Conclusions/SignificanceFormation of new vessels in fat tissues during DIO is largely due to angiogenesis rather than de novo vasculogenesis. Antiangiogenic treatment by blockade of VEGFR2 but not VEGFR1 may limit adipose tissue expansion.

Background and Objectives: 5-Aminolevulinic acid (ALA) and methyl aminolevulinate (MAL) are porphyrin precursors used topically for photodynamic therapy (PDT). Previous studies have established that ablative fractional laser (AFXL) increases topical drug uptake. We evaluated kinetics and biodistribution of ALA-and MAL-induced porphyrins on intact and disrupted skin due to AFXL. Materials and Methods: Two Yorkshire swine were exposed to CO 2 AFXL (10.6 mm, 1,850 mm ablation depth) and subsequent topical application of ALA and MAL cream formulations (20%, weight/weight). Porphyrin fluorescence was quantified by digital fluorescence photography (30, 90, and 180 minutes) and fluorescence microscopy at specific skin depths (180 minutes). Results: Porphyrins gradually formed over time, differently on intact and AFXL-disrupted skin. On intact skin (no AFXL), fluorescence photography showed that MAL initially induced higher fluorescence than ALA (t ¼ 30 minutes MAL 21.1 vs. ALA 7.7 au, t ¼ 90 minutes MAL 39.0 vs. ALA 26.6 (P < 0.009)) but reached similar intensities for long-term applications (t ¼ 180 minutes MAL 56.6 vs. ALA 52 au, P ¼ ns). AFXL considerably enhanced porphyrin fluorescence from both photosensitizers (P < 0.05). On AFXL-exposed skin, MAL expressed higher fluorescence than ALA for short-term application (t ¼ 30 minutes, AFXL-MAL 26.4 vs. AFXL-ALA 14.1 au, P < 0.001), whereas ALA over time overcame MAL and induced the highest fluorescence intensities obtained (t ¼ 180 minutes, AFXL-MAL 98.6 vs. AFXL-ALA 112.0 au, P < 0.001). In deep skin layers, fluorescence microscopy showed higher fluorescence in hair follicle epithelium for ALA than MAL (t ¼ 180 minutes, 1.8 mm, AFXL-MAL 35.3 vs. AFXL-ALA 46.7 au, P < 0.05). Conclusions: AFXL changes kinetics and biodistribution of ALA and MAL. It appears that AFXL-ALA favors targeting deep structures.

Summary We have developed a physiologically-based mathematical model, with parameters derived from published experimental data, to simulate the regulatory effects of the leptin pathway on murine energy homeostasis. Model outcomes are consistent with data reported in the literature, and reproduce key characteristics of the energy regulatory system, including compensatory responses that counteract changes in body weight, and the failure of this ability when the leptin pathway is disrupted. Our model revealed the possibility of multiple steady states for body weight. It also provided a unified theoretical framework for two historically antagonistic hypotheses regarding body weight regulation (“set-point” vs. “settling point”). Finally, our model has identified potential avenues for future investigations.

In addition to providing a physical barrier, skin also serves a diverse range of physiological functions through different specialized resident cell types/structures, including melanocytes (pigmentation and protection against ultraviolet radiation), Langerhans cells (adaptive immunity), fibroblasts (maintaining extracellular matrix, paracrine regulation of keratinocytes), sweat glands (thermoregulation) and hair follicles (hair growth, sensation and a stem cell reservoir). Restoration of these functional elements has been a long‐standing challenge in efforts to engineer skin tissue, while autologous skin grafting is limited by the scarcity of donor site skin and morbidity caused by skin harvesting. We demonstrate an alternative approach of harvesting and then implanting μm‐scale, full‐thickness columns of human skin tissue, which can be removed from a donor site with minimal morbidity and no scarring. Fresh human skin microcolumns were used to reconstitute skin in wounds on immunodeficient mice. The restored skin recapitulated many key features of normal human skin tissue, including epidermal architecture, diverse skin cell populations, adnexal structures and sweat production in response to cholinergic stimulation. These promising preclinical results suggest that harvesting and grafting of microcolumns may be useful for reconstituting fully functional skin in human wounds, without donor site morbidity. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.