A histidine-rich elastin-like polypeptide functions as a quickly detectable and easily purifiable protein fusion tag.

Although many protein fusion tags have been developed for recombinant protein production to improve protein yields or facilitate purification, determining the expression and purification of the fusion protein still remain to be a time-consuming and laborious procedure. In this work, we designed a histidine-rich elastin-like polypeptide (HRELP) fusion tag and found that it could be efficiently expressed in E. coli cells and specifically stained with Pauly's reagent in a couple of minutes post SDS-PAGE analysis. Moreover, in Pauly's reagent-stained polyacrylamide gels, only the bands of HRELP fusion proteins were yellow and could be clearly visualized with little background. Furthermore, both HRELPs and HRELP20-BMP2 fusion protein could be purified by a method of pH shift-mediated inverse transition cycling (ITC). In our opinion, the HRELP established in this study may be considered as a multifunctional protein tag which could make its fusion proteins being quickly detected by Pauly staining and simply purified by pH-triggered ITC in addition to having the potential to sustained release its fusion proteins.

Growth Factor-Reinforced ECM Fabricated from Chemically Hypoxic MSC Sheet with Improved In Vivo Wound Repair Activity.

MSC treatment can promote cutaneous wound repair through multiple mechanisms, and paracrine mediators secreted by MSC are responsible for most of its therapeutic benefits. Recently, MSC sheet composed of live MSCs and their secreted ECMs was reported to promote wound healing; however, whether its ECM alone could accelerate wound closure remained unknown. In this study, Nc-ECM and Cc-ECM were prepared from nonconditioned and CoCl2-conditioned MSC sheets, respectively, and their wound healing properties were evaluated in a mouse model of full-thickness skin defect. Our results showed that Nc-ECM can significantly promote wound repair through early adipocyte recruitment, rapid reepithelialization, enhanced granulation tissue growth, and augmented angiogenesis. Moreover, conditioning of MSC sheet with CoCl2 dramatically enriched its ECM with collagen I, collagen III, TGF-ß1, VEGF, and bFGF via activation of HIF-1α and hence remarkably improved its ECM's in vivo wound healing potency. All the Cc-ECM-treated wounds completely healed on day 7, while Nc-ECM-treated wounds healed about 85.0% ± 8.6%, and no-treatment wounds only healed 69.8% ± 9.6% (p < 0.05). Therefore, we believe that such growth factor-reinforced ECM fabricated from chemically hypoxic MSC sheet has the potential for clinical translation and will lead to a MSC-derived, cost-effective, bankable biomaterial for wound management.

Evaluation of xenogeneic extracellular matrix fabricated from CuCl2-conditioned mesenchymal stem cell sheets as a bioactive wound dressing material.

The extracellular matrix has drawn considerable interest in tissue engineering not only acts as a bioactive three-dimensional scaffold but also regulates cell behaviors through providing biochemical signals. Extracellular matrix-based biomaterials, mainly derived from xenogeneic tissues, have shown positive outcomes in promoting cutaneous wound healing. However, such extracellular matrices only contain low doses of growth factors, which limit their therapeutic efficiency. Recent reports demonstrated that cell sheets made from mesenchymal stem cell can accelerate wound repair through enhanced re-epithelialization and angiogenesis, but its clinical translation is hindered by several limitations, such as the risk of aberrant immune responses and cost implications. In this study, acellular extracellular matrices were prepared from CuCl2-conditioned mesenchymal stem cell sheets and their in vivo wound healing properties were evaluated in a mouse model of full-thickness skin defect. We found that extracellular matrices derived from CuCl2-conditioned mesenchymal stem cell sheets have a compact surface with thick solid-like cross-sectional structure. Moreover, CuCl2 dramatically enriched the extracellular matrices with collagen I, collagen III, transforming growth factor-ß1, vascular endothelial growth factor, and basic fibroblast growth factor via hypoxia-inducible factor-1α activation. And as a consequence, the resulting extracellular matrices showed markedly improved in vivo wound healing potency through early adipocyte mobilization, enhanced granulation tissues formation, rapid re-epithelialization, and augmented angiogenesis. Therefore, we consider that the extracellular matrix derived from CuCl2-conditioned mesenchymal stem cell sheets has the potential for clinical translation and may lead to a novel strategy for wound management.

Enzymatically catalyzed synthesis of anti-blooming agent 1,3-dibehenoyl-2-oleoyl glycerol in a solvent-free system: optimization by response surface methodology.

Products rich in 1,3-dibehenoyl-2-oleoyl glycerol (BOB) triglyceride (TAG) were produced by enzymatic interesterification of high oleic acid sunflower oil (HOSO) and behenic acid methyl ester (BME) by 1,3-regiospecific lipase Lipozyme RM IM in a solvent-free system. The impact factors of enzyme load, substrate molar ratio of BME to HOSO (BME/HOSO), reaction time, reaction temperature, and pre-equilibration water activity of the enzyme on BOB content and BME conversions were investigated by single-factor experiments and then optimized using the response surface methodology (RSM). The optimum conditions were as follows: reaction temperature, 72 °C; reaction time, 7.99 h; substrate molar ratio, 2.5:1; enzyme load, 10%; and pre-equilibration water activities of the enzyme, 0.28. The results from the experiments conducted according to the predicted optimal conditions were as follows: the content of BOB was 32.76%, and the conversion of BME was 65.16%. The experimental values agreed with the predicted values, which verified the sufficiency of the quadratic regression models. After purification under the optimal short-range molecular distillation and two-step solvent fractionation, the content of BOB in the target product can reach 77.14%, indicating the great potential for industrial production of the anti-blooming agent.

Treatment of alopecia by transplantation of hair follicle stem cells and dermal papilla cells encapsulated in alginate gels.

The affected individual of hair loss demands help, because hair is viewed as a sign of youth and good health. Nowadays treatment of alopecia includes drug therapy and hair transplantation. Some drugs may promote hair growth, at least temporarily, but the treatment is effective only in milder alopecia, instead of extensive alopecia. Furthermore, the side effect of long period medication could not be avoided. Hair transplantation involves harvesting small pieces of hair-bearing scalp grafts from a donor site and relocating them to a bald area. This method does not increase the number of existing hairs, but only redistributes them. The operation is sophisticated and time-consuming, thus the patient suffers a lot during the process. The discovery of hair follicle stem cells (FSC) brings gospel to the affected individual of hair loss because of its capacity of generating new hair when they interact with mesenchymal dermal papilla cells (DPC). Besides, both FSC and DPC have strong proliferative capacity and the patient's own cells could be expanded considerably in vitro. Thus we hypothesize that the microencapsulation of the two kinds of cells in alginate gels could be implanted into the bald scalp of the patient since alginate gels is effective in cell transplantation. The strategy may provide a more convenient and valid alternative to hair loss if the hypothesis proved to be practical.