Enhanced Diabetic Rat Wound Healing by Platelet-Rich Plasma Adhesion Zwitterionic Hydrogel.

BACKGROUND: The skin is the largest organ in the human body and serves as a barrier for protective, immune, and sensory functions. Continuous and permanent exposure to the external environment results in different levels of skin and extracellular matrix damage. During skin wound healing, the use of good dressings and addition of growth factors to the wound site can effectively modulate the rate of wound healing. A dressing containing bioactive substances can absorb wound exudates and reduce adhesion between the wound and dressing, whereas growth factors, cytokines, and signaling factors can promote cell motility and proliferation. AIM AND OBJECTIVES: We prepared a functional wound dressing by combining platelet-rich plasma (PRP) and zwitterionic hydrogels. Functional wound dressings are rich in various naturally occurring growth factors that can effectively promote the healing process in various types of tissues and absorb wound exudates to reduce adhesion between wounds and dressings. Furthermore, PRP-incorporated zwitterionic hydrogels have been used to repair full-thickness wounds in Sprague-Dawley rats with diabetes (DM SD). MATERIALS AND METHODS: Fibroblasts and keratinocytes were cultured with PRP, zwitterionic hydrogels, and PRP-incorporated zwitterionic hydrogels to assess cell proliferation and specific gene expression. Furthermore, PRP-incorporated zwitterionic hydrogels were used to repair full-thickness skin defects in DM SD rats. RESULTS: The swelling ratio of hydrogel, hydrogel + PRP1000 (108 platelets/mL), and hydrogel + PRP1000 (109 platelets/mL) groups were similar (~07.71% ± 1.396%, 700.17% ± 1.901%, 687.48% ± 4.661%, respectively) at 144 hours. The tensile strength and Young modulus of the hydrogel and hydrogel + PRP10000 groups were not significantly different. High concentrations of PRP (approximately 108 and 109 platelets/mL) effectively promoted the proliferation of fibroblasts and keratinocytes. The zwitterionic hydrogels were not cytotoxic to any cell type. High PRP concentration-incorporated zwitterionic hydrogels increased the rate of cell proliferation and significantly increased the expression of characteristic genes such as collagen, fibronectin, involucrin, and keratin. Subsequently, zwitterionic hydrogels with high PRP concentrations were used to repair full-thickness skin defects in DM SD rats, and a wound healing rate of more than 90% was recorded on day 12. CONCLUSIONS: PRP contains high concentrations of growth factors that promote cell viability, enhance specific gene expression, and have a high medical value in cell therapy. Zwitterionic hydrogels have a 3-dimensional interconnected microporous structure and can resist cell adhesion without causing cytotoxicity. Platelet-rich plasma-incorporated zwitterionic hydrogels further enhance the cellular properties and provide an effective therapeutic option for wound healing.

Planar-/Curvilinear-Bioprinted Tri-Cell-Laden Hydrogel for Healing Irregular Chronic Wounds.

Chronic cutaneous wounds from tissue trauma or extensive burns can impair skin barrier function and cause severe infection. Fabrication of a customizable tissue-engineered skin is a promising strategy for regeneration of uneven wounds. Herein, a planar-/curvilinear-bioprintable hydrogel is developed to produce tissue-engineered skin and evaluated in rat models of chronic and irregular wounds. The hydrogel is composed of biodegradable polyurethane (PU) and gelatin. The hydrogel laden with cells displays good 3D printability and structure stability. The circular wounds of normal and diabetes mellitus (DM) rats treated with planar-printed tri-cell-laden (fibroblasts, keratinocytes, and endothelial progenitor cells (EPCs)) hydrogel demonstrate full reepithelization and dermal repair as well as large amounts of neovascularization and collagen production after 28 days. Furthermore, the curvilinear module is fabricated based on the corresponding wound topography for curvilinear-bioprinting of the irregular tissue-engineered skin. The large and irregular rat skin wounds treated with curvilinear-printed tri-cell-laden hydrogel demonstrate full repair after 28 days. This planar-/curvilinear-bioprintable tri-cell-laden hydrogel shows great potential for customized biofabrication in skin tissue engineering.

An In Vitro Study of the Effects of Mechanical and Enzymatic Isolation of Stromal Vascular Fraction on Wound Healing.

ABSTRACT: The adipose-derived stromal vascular fraction (SVF) is considered to be an attractive source of stem cells in cell therapy. Besides stem cells, it also contains functional cells, such as macrophages, precursor cells, somatic stem cells, and pericytes. Collagenase digestion is the most frequently used method to isolate SVF, but it is time-consuming and costly and has some problems, such as infectious agents and immune reactions. In this research, we compared the yield, cell population ratios, and cell viability when isolating SVF by the ultrasonic physics (U-SVF) method and traditional enzymatic method (E-SVF). Then, we isolated exosomes from U-SVF and E-SVF, respectively, and cocultured them with fibroblasts to investigate the potential of applying this cell secretion in wound repair. The results showed that there was no significant difference between the ultrasonic method and enzymatic method in terms of cell viability, cell numbers, or the expression of CD markers of stem cells. However, exosome analysis identified a greater number and smaller size of exosome particles obtained by U-SVF. In terms of cell proliferation efficiency, although the proliferation efficiency of U-SVF was lower than that of E-SVF. Trilineage differentiation experiments revealed that both E-SVF and U-SVF had good differentiation ability, owing to high stem cell content. Finally, E-SVF and U-SVF exosomes were cocultured with fibroblasts. The efficiency of fibroblast migration increased in the SVF exosome treated groups, and the expression of related genes (integrin α5ß1) was slightly upregulated; however, the expression of FAK, AKT, ERK, and RhoA was significantly upregulated at 24 hours. From the abovementioned experiments, we found that there was no significant difference in stem cell-related characteristics between SVF isolated by ultrasonic cavitation and SVF isolated by the enzymatic method. In addition, exosomes secreted by SVF may have excellent therapeutic effect on skin injuries, which provides a new viewpoint and therapeutic strategy for soft tissue repair.

Beneficial Effects of Astragaloside IV-Treated and 3-Dimensional-Cultured Endothelial Progenitor Cells on Angiogenesis and Wound Healing.

INTRODUCTION: Astragaloside IV (AS-IV) is a natural herb extract and a popular compound used in traditional Chinese medicine because of its effect on multiple biological processes, such as promotion of cell proliferation, improvement in cardiopulmonary and vascular function, and promotion of angiogenesis around wounds, leading to accelerated wound healing. Vascular regeneration primarily results from the differentiation of endothelial progenitor cells (EPCs). Biomedical acceleration of angiogenesis and differentiation of EPCs around the wound remain challenging. MATERIALS AND METHODS: In this study, we treated human umbilical cord blood-derived EPCs with AS-IV and cultured them on 2-dimensional (tissue culture polystyrene) and 3-dimensional culture plates (3DPs). These cultured cells were then combined with human blood plasma gel and applied on the skin of nude mice in an attempt to repair full-thickness skin defects. RESULTS: The results show that using 3DP culture could increase vascular-related gene expression in EPCs. Furthermore, 12.5 µg/mL AS-IV-treaded EPCs were combined with plasma gels (P-3DP-EPC12.5) and showed enhanced vascular-related protein expression levels after 3 days of culture. Finally, P-3DP-EPC12.5s were used to repair full-thickness skin defects in nude mice, and we could register a wound healing rate greater than 90% by day 14. CONCLUSIONS: Based on these results, we concluded that we have developed a potential therapeutic approach for wound healing using plasma gel containing 3-dimensional surface-cultured AS-IV-treated EPCs.

Evaluation of Polycaprolactone/Gelatin/Chitosan Electrospun Membrane for Peritoneal Adhesion Reduction.

In this study, a novel antiadhesion membrane made of polycaprolactone, gelatin, and chitosan was fabricated using the electrospinning technique. A series of polycaprolactone/gelatin/chitosan (PGC) electrospun membranes with different amounts of chitosan (0%, 0.5%, 1%, and 2% in weight percentage) was synthesized. The physicochemical properties and biocompatibility of the fabricated membranes were examined and compared with the aim to select an effective antiadhesion membrane. Scanning electron microscopy showed that these 4 electrospun membranes had similar fiber diameter and pore area, with no statistical differences between them. Furthermore, the contact angle decreased with increased chitosan content, indicating that chitosan may contribute to increased hydrophilic properties. The in vitro degradation test revealed that the higher chitosan content corresponded to a lower degradation rate in PGC membranes within 7 days. All PGC membranes exhibited similar cell proliferation; however, cell proliferation was lower than tissue culture polystyrene (P < 0.05). To compare antiadhesion ability, the adhesion between the cecum and abdominal wall was created in a rat model. Assessment after implantation of electrospun membranes revealed that PGCs with higher chitosan content (PGC2) had better antiadhesion effects, as evaluated by an adhesion score at day 14 postsurgery. Thus, PGC2 was effective in reducing the formation of tissue adhesion. Therefore, PGC electrospun membrane may provide a potential peritoneal antiadhesion barrier for clinical use.

Methylglyoxal induces cell death through endoplasmic reticulum stress-associated ROS production and mitochondrial dysfunction.

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are two important leading causes of acquired blindness in developed countries. As accumulation of advanced glycation end products (AGEs) in retinal pigment epithelial (RPE) cells plays an important role in both DR and AMD, and the methylglyoxal (MGO) within the AGEs exerts irreversible effects on protein structure and function, it is crucial to understand the underlying mechanism of MGO-induced RPE cell death. Using ARPE-19 as the cell model, this study revealed that MGO induces RPE cell death through a caspase-independent manner, which relying on reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP) loss, intracellular calcium elevation and endoplasmic reticulum (ER) stress response. Suppression of ROS generation can reverse the MGO-induced ROS production, MMP loss, intracellular calcium increase and cell death. Moreover, store-operated calcium channel inhibitors MRS1845 and YM-58483, but not the inositol 1,4,5-trisphosphate (IP3) receptor inhibitor xestospongin C, can block MGO-induced ROS production, MMP loss and sustained intracellular calcium increase in ARPE-19 cells. Lastly, inhibition of ER stress by salubrinal and 4-PBA can reduce the MGO-induced intracellular events and cell death. Therefore, our data indicate that MGO can decrease RPE cell viability, resulting from the ER stress-dependent intracellular ROS production, MMP loss and increased intracellular calcium increase. As MGO is one of the components of drusen in AMD and is the AGEs adduct in DR, this study could provide a valuable insight into the molecular pathogenesis and therapeutic intervention of AMD and DR.