Preservation of Small Extracellular Vesicle in Gelatin Methacryloyl Hydrogel Through Reduced Particles Aggregation for Therapeutic Applications.

PURPOSE: Small extracellular vesicles (sEV) play an irreplaceable role in cell-cell communication. However, sEV in solution aggregate with each other during preservation, leading to impairment of the structures, contents, and functions of sEV. Therefore, there is a need to develop an optimal preservation method that combines high recovery rate, low cost, convenience, and easy-transportation in one. In this study, a new preservation strategy different from the cryopreservation or lyophilization was developed by reducing sEV particles aggregation. METHODS: The sEV were encapsulated in thermoresponsive gelatin methacryloyl (GelMA) hydrogels at 4°C to reduce particles aggregation during the reversible cross-linking process. The sEV movement was visualized in different mediums and particles' number, size, structure and protein of 28 days preserved sEV were compared to fresh sEV. Human umbilical vein endothelial cells (HUVEC) and rat adipose-derived stromal stem cells (rASC) were isolated and cultured with fresh and preserved sEV to test the cellular response. A mice subcutaneous model was adopted to detect controlled release and angiogenesis ability of preserved sEV. RESULTS: Through particles tracks visualization, GelMA hydrogels significantly decreased the sEV movement. After 28 days preservation in GelMA at 4°C, the particles number, size, structure and protein of sEV were similar to fresh sEV. In vitro, preserved sEV had the same ability to promote cell proliferation, migration and angiogenesis as fresh sEV. In vivo, preserved sEV-GelMA could artificially regulate the absorptivity of GelMA hydrogels and controlled released sEV for therapeutic application, and preserved sEV encapsulated in GelMA significantly promoted angiogenesis in mice. CONCLUSION: Our results demonstrated that sEV encapsulated in GelMA could be a novel strategy for long-term preservation of sEV for therapeutic application.

The Effect of Different Diameters of Fat Converters on Adipose Tissue and Its Cellular Components: Selection for Preparation of Nanofat.

BACKGROUND: Nanofat is an autologous product prepared mechanically from harvested fat. In nanofat grafting, converters are employed for mechanical emulsification to facilitate fat injection. To date, the study of different converters has received scant attention regarding whether they affect the characteristics of nanofat in terms of the practical applications and indications. OBJECTIVES: The authors set out to investigate the influence of different internal diameters of converters on biological functionality of nanofat during shuffling. METHODS: The 3-dimensional finite element method was employed to simulate the process of mechanical emulsification of fat and to research the stress with 5 different converters (3.76 mm, 2.00 mm, 1.20 mm, 1.00 mm, 0.80 mm). An assessment of the morphology of emulsified fat was conducted. Isolated stromal vascular fraction (SVF) was analyzed for cellular components, number, and viability through flowcytometry and live/ dead staining. Adipocytic and angiogenic differentiation assay allowed assessment of differentiation capacity of the SVF. RESULTS: The smaller the aperture of the converter, the greater the mechanical force on adipose tissue during mechanical emulsification, showing the different macroscopic and microscopic structure of the emulsified fat. No difference in viability or ratio of endothelial progenitor cells and other cells was found. Angiogenic and adipogenic differentiation capacity of the SVF significantly changed in 5 different converters. CONCLUSIONS: The mechanical emulsification from different apertures of converters exerts different effects of adipose tissue structure, cell content, and multipotency differentiation but not its viability. Converters with different apertures can be selected according to clinical needs.

Prospective application of exosomes derived from adipose-derived stem cells in skin wound healing: A review.

BACKGROUND: Wound healing has always been an intractable medical problem for both clinicians and researchers and a burden for patients both physically and financially. Poor wound healing at the injury site, especially in an exposed site, is associated with an unappealing esthetic appearance in patients and also results in a bad skin barrier, tissue infection and necrosis, loss of main function in extreme cases and other serious local and systemic consequences. There is a crucial and urgent need for newer, more efficacious methods for enhancing the healing process to achieve optimal outcomes morphologically and functionally. Recent advances have focused on developing therapies that promote tissue regeneration through positively activating the mechanism of tissue repair. Given the increasing high-quality studies concerning exosomes derived from adipose-derived stem cells (ADSCs-Exos), their potential use in accelerating or supporting the wound healing process has gained increasing attention in recent years. AIMS: In this review, we present an overview of the recent advances in the field of ADSCs-Exos and investigate their benefit in wound healing for skin regeneration with the expectation of providing a perspective on how to best utilize this powerful cell-free therapy in the future. METHODS: A retrospective review of the published data was conducted. RESULTS: Most studies have shown the possible roles of ASCs-derived exosomes (ADSCs-Exos) in cutaneous wound healing through regulation of the inflammatory response and promotion of cell proliferation, migration, differentiation, angiogenesis and matrix reconstruction to provide a new perspective strategy for the use of ASCs-Exos in skin wound healing. CONCLUSION: ADSCs-Exos are likely to achieve the best functionally and cosmetic skin wound healing while avoiding undesirable consequences. ADSCs-Exos represent a novel therapeutic tool in soft tissue repair; however, further randomized, double-blind, comparative clinical trials must be performed to determine the specific mechanisms, safety and other relevant cosmetic concerns.

Comparison of the Microstructures and Properties of Different Microcannulas for Hyaluronic Acid Injection.

BACKGROUND: Microcannulas are used for hyaluronic acid and other filler injections and reduce the side effects and complications. There are several microcannulas and the differences between microcannulas have not been carefully investigated. The purpose of this study was to compare the microstructures and properties of different microcannulas by several trials and provide guidance for clinical application. METHODS: Nine types of microcannulas from different manufacturers were chosen. Scanning electron microscopy was used to obtain high-definition images of microstructures, chemical composition analyzers were used to test the chemical composition of the tips, and a universal testing machine was used to measure mechanical properties. The injection speed test recorded the time spent for the weight to push hyaluronic acid out of microcannulas. The vessel piercing force test was conducted to simulate the process of puncturing the vessels in vitro. RESULTS: The scanning electron microscopic images showed the tip shapes and inner surfaces that may relate to the characteristics. The chemical composition of most microcannulas met the American Society for Testing and Materials standards basically. The mechanical properties were obviously different. The results of the injection speed test were discrepant more than seven times. The vessel piercing test showed which microcannula was the most difficult and easiest to puncture the aorta. CONCLUSIONS: The results indicated that there are significant differences between different microcannulas. The differences are instructive to physicians for selecting suitable microcannulas to improve the injection effect and reduce discomfort and complications. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

[Adhesion of Streptococcus mutans to removable denture crowns].

OBJECTIVE: To determine adhesion of Streptococcus mutans (S. mutans) to different kinds of removable denture crowns for the purpose of minimizing influence of removable denture on oral environment. METHODS: Three kinds of removable denture crowns (single color synthetic resin teeth, alloy pin porcelain tooth and minute color synthetic resin teeth) were adsorbed S. mutans for 24 h in sterile saliva, The adhered bacteria were counted by means of sonic oscillation and bacteria coating. RESULTS: Highest level of adhesion was found on ,the single color synthetic resin teeth was adsorbed mostly, followed by alloy pin porcelain teeth. Minute color synthetic resin teeth had far less adhesion than the others (P<0.01). CONCLUSION: Minute color synthetic resin teeth have less adhesion of S. mutans, which may be associated with their lower level of surface free energy.