Self-Assembled DNA Composite-Engineered Mesenchymal Stem Cells for Improved Skin-Wound Repair.

The direct use of mesenchymal stem cells (MSCs) as therapeutics for skin injuries is a promising approach, yet it still faces several obstacles, including limited adhesion, retention, and engraftment of stem cells in the wound area, as well as impaired regenerative and healing functions. Here, DNA-based self-assembled composites are reported that can aid the adhesion of MSCs in skin wounds, enhance MSC viability, and accelerate wound closure and re-epithelialization. Rolling-circle amplification (RCA)-derived DNA flowers, equipped with multiple copies of cyclic Arg-Gly-Asp (cRGD) peptides and anti-von Willebrand factor (vWF) aptamers, act as robust scavengers of reactive oxygen species (ROS) and enable synergistic recognition and adhesion to stem cells and damaged vascular endothelial cells. These DNA structure-aided stem cells are retained at localized wound sites, maintain repair function, and promote angiogenesis and growth factor secretion. In both normal and diabetes-prone db/db mice models with excisional skin injuries, facile topical administration of DNA flower-MSCs elicits rapid blood vessel formation and enhances the sealing of the wound edges in a single dose. DNA composite-engineered stem cells warrant further exploration as a new strategy for the treatment of skin and tissue damage.

[Application of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet].

Objective: To explore the feasibility and effectiveness of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet. Methods: Between July 2017 and January 2023, 35 cases of hand and foot defects were repaired with plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue (13 pedicled flaps and 22 free flaps). There were 18 males and 17 females, with an average age of 38.8 years (range, 8-56 years). Thirty cases of defects were caused by trauma, and the interval between injury and admission ranged from 2 to 6 hours (mean, 3.3 hours). Three cases were ulcer wounds with a course of 3.0, 3.8, and 7.0 months, respectively. Two cases were malignant melanoma. Eight cases of wounds located in the fingers, 13 cases in the palm, 12 cases in the heel, and 2 cases in the distal foot. The size of skin defects ranged from 4.0 cm×3.5 cm to 12.0 cm×10.0 cm, and the size of flap ranged from 5.0 cm×4.5 cm to 13.0 cm×11.0 cm. The donor sites were repaired with skin grafts. Results: All flaps were survived and the wounds healed by first intention after operation. The partial necrosis at the edge of the skin graft occurred in 1 case, which healed after dressing change; the other skin grafts survived successfully. All patients were followed up 6-24 months (mean, 18 months). The flaps exhibited similar color and thickness to the surrounding hand and foot skin. Two-point discrimination ranged from 7 to 10 mm in the flaps with an average of 8 mm. The donor sites had no painful scars or sensory abnormalities. Foot and ankle functions were good and gaits were normal. Conclusion: Application of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet had good flap shape, high survival rate of skin graft at the donor site, and no obvious complications.

Highly Elastic and Strain Sensing Corn Protein Electrospun Fibers for Monitoring of Wound Healing.

Due to the lack of sufficient elasticity and strain sensing capability, protein-based ultrafine fibrous tissue engineering scaffolds, though favorable for skin repair, can hardly fulfill on-spot wound monitoring during healing. Herein, we designed highly elastic corn protein ultrafine fibrous smart scaffolds with a three-layer structure for motion tracking at an unpackaged state. The densely cross-linked protein networks were efficiently established by introducing a highly reactive epoxy and provided the fiber substrates with wide-range stretchability (360% stretching range) and ultrahigh elasticity (99.91% recovery rate) at a wet state. With the assistance of the polydopamine bonding layer, a silver conductive sensing layer was built on the protein fibers and endowed the scaffolds with wide strain sensing range (264%), high sensitivity (gauge factor up to 210.55), short response time (<70 ms), reliable cycling stability, and long-lasting duration (up to 30 days). The unpackaged smart scaffolds could not only support cell growth and accelerate wound closure but also track motions on skin and in vivo and trigger alarms once excessive wound deformations occurred. These features not only confirmed the great potential of these smart scaffolds for applications in tissue reconstruction and wound monitoring but also proved the possibility of employing various plant protein ultrafine fibers as flexible bioelectronics.

Applications of MXene and its modified materials in skin wound repair.

The rapid healing and repair of skin wounds has been receiving much clinical attention. Covering the wound with wound dressing to promote wound healing is currently the main treatment for skin wound repair. However, the performance of wound dressing prepared by a single material is limited and cannot meet the requirements of complex conditions for wound healing. MXene is a new two-dimensional material with electrical conductivity, antibacterial and photothermal properties and other physical and biological properties, which has a wide range of applications in the field of biomedicine. Based on the pathophysiological process of wound healing and the properties of ideal wound dressing, this review will introduce the preparation and modification methods of MXene, systematically summarize and review the application status and mechanism of MXene in skin wound healing, and provide guidance for subsequent researchers to further apply MXene in the design of skin wound dressing.

Skin Wound Healing: Of Players, Patterns, and Processes.

BACKGROUND: Wound healing of the skin is a very complex biological activity. For a better understanding, an attempt is made to describe and subdivide the different players (cell types and signaling molecules), patterns (different regeneration or repair mechanisms), and processes (division of the overall process into categories, phases, and steps). However, this is always based on different points of view. On the one hand, the temporality of the phases and on the other hand, the dominant activity in each step can play a role. In addition, classifications according to wound theory and wound treatment are possible. SUMMARY: To gain an initial overview of (human) skin wound healing, simple classifications are advantageous for understanding and thus deserve to exist. The complexity of the underlying biology of skin wound healing takes on a multidimensional configuration upon closer examination, in which new actors are constantly being identified, making the events more precise and comprehensible but also significantly confusing when viewed as a whole. From this point of view, the healing process must be categorized so that the observer does not get lost in the multitude of interacting processes. In view of the steadily increasing knowledge, which includes in parallel the physiological as well as the pathophysiological processes of wound healing, the classification according to function in the sense of consecutive and overlapping phases seems the most convenient and considers the corresponding processes more precisely. Despite that many mechanisms and specific cellular functions in wound healing have been identified, many underlying (patho-)physiological processes still remain unknown. KEY MESSAGES: Currently, a substantial part of research activities in medicine is limited to molecular levels, while evidence for therapies currently in use is lacking or newly gained knowledge is quite far from clinical applicability and reality. This article aimed to shed more light on the various classifications of skin wound healing and presents the underlying paradigms starting from simple approaches and ending with more detailed concepts.

Application of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet / 中国修复重建外科杂志

OBJECTIVE@#To explore the feasibility and effectiveness of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet.@*METHODS@#Between July 2017 and January 2023, 35 cases of hand and foot defects were repaired with plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue (13 pedicled flaps and 22 free flaps). There were 18 males and 17 females, with an average age of 38.8 years (range, 8-56 years). Thirty cases of defects were caused by trauma, and the interval between injury and admission ranged from 2 to 6 hours (mean, 3.3 hours). Three cases were ulcer wounds with a course of 3.0, 3.8, and 7.0 months, respectively. Two cases were malignant melanoma. Eight cases of wounds located in the fingers, 13 cases in the palm, 12 cases in the heel, and 2 cases in the distal foot. The size of skin defects ranged from 4.0 cm×3.5 cm to 12.0 cm×10.0 cm, and the size of flap ranged from 5.0 cm×4.5 cm to 13.0 cm×11.0 cm. The donor sites were repaired with skin grafts.@*RESULTS@#All flaps were survived and the wounds healed by first intention after operation. The partial necrosis at the edge of the skin graft occurred in 1 case, which healed after dressing change; the other skin grafts survived successfully. All patients were followed up 6-24 months (mean, 18 months). The flaps exhibited similar color and thickness to the surrounding hand and foot skin. Two-point discrimination ranged from 7 to 10 mm in the flaps with an average of 8 mm. The donor sites had no painful scars or sensory abnormalities. Foot and ankle functions were good and gaits were normal.@*CONCLUSION@#Application of plantar medial thin skin flaps preserving plantar fascia with its superficial fascia tissue to repair skin defects in hands and feet had good flap shape, high survival rate of skin graft at the donor site, and no obvious complications.

Advances in wound repair and regeneration: Systematic comparison of cell free fat extract and platelet rich plasma.

Background: Previous studies showed Cell free fat extract (CEFFE) and Platelet rich plasma (PRP) could effectively accelerate wound healing. However, the comparative study on curative effect is still lacking. A systematic comparison could provide more theoretical support and laboratory basis for the clinical application of CEFFE and PRP. Objective: To compare the efficacy of CEFFE and PRP in promoting skin wound repair. Methods: CEFFE and PRP were prepared according to the literature. The wound repair related factors were measured and compared. In vitro, the effects of both on cell migration, proliferation and tube formation were compared. In vivo, wound healing rate was measured on the 1st, 3rd, 9th, and 12th days after skin injury and treatment. Then the specimens were cut off for histological analysis. Results: Although the total protein content of PRP was significantly around 19 times higher than that of CEFFE, there was no statistical difference in the content of BDNF, EGF and VEGF between CEFFE and PRP. Even the NT-3 content of CEFFE was just slightly higher than that of PRP. The concentration of b-FGF, HGF and TGF-ß and PDGF-BB in PRP is higher than that in CEFFE, but there is only a very small difference between them. In vitro, PRP showed better efficacy than CEFFE in promoting fibroblast proliferation while there was no significant difference in promoting angiogenesis and fibroblast migration. Both PRP and CEFFE could significantly promote wound healing in mice. There was no statistical difference in wound healing between CEFFE and PRP groups in vivo. Immunohistochemical staining of Ki67&CD31 showed that there was no significant difference between PRP and CEFFE groups. Conclusion: The effect of PRP and CEFFE in promoting wound healing was similar. In clinical practice, the acquisition of PRP is relatively more convenient. Containing no cells, CEFFE has the advantage of easier preservation. For patients who have discarded adipose tissue, or contraindications to PRP technology, CEFFE technology may provide a new option for skin wound repair.

Hypoxic ucMSC-secreted exosomal miR-125b promotes endothelial cell survival and migration during wound healing by targeting TP53INP1.

A hypoxic microenvironment is a common feature of skin wounds. Our previous study demonstrated that three-dimensional coculture of umbilical cord-derived mesenchymal stem cells (ucMSCs) and endothelial cells facilitates cell communication and host integration in skin tissue engineering. Here, we aimed to identify the mechanism by which ucMSCs affect endothelial cells under hypoxic conditions after skin injury. We demonstrate that hypoxia enhances the exosome-mediated paracrine function of ucMSCs, which increases endothelial cell proliferation and migration. In a mouse full-thickness skin injury model, ucMSC-derived exosomes can be taken up by endothelial cells and accelerate wound healing. Hypoxic exosomes lead to a better outcome than normoxic exosomes by promoting proliferation and inhibiting apoptosis. Mechanistically, microRNA-125b (miR-125b) transcription is induced by hypoxia in ucMSCs. After being packaged into hypoxic exosomes and transported to endothelial cells, miR-125b targets and suppresses the expression of tumor protein p53 inducible nuclear protein 1 (TP53INP1) and alleviates hypoxia-induced cell apoptosis. Inhibition of miR-125b-TP53INP1 interaction attenuates the protective effect of hypoxic exosomes. Moreover, artificial agomiR-125b can accelerate wound healing in vivo. Our findings reveal communication between ucMSCs and endothelial cells via exosomal miR-125b/TP53INP1 signaling in the hypoxic microenvironment and present hypoxic exosomes as a promising therapeutic strategy to enhance cutaneous repair.

Staphylococcus aureus impairs cutaneous wound healing by activating the expression of a gap junction protein, connexin-43 in keratinocytes.

Chronic wounds have been considered as major medical problems that may result in expensive healthcare. One of the common causes of chronic wounds is bacterial contamination that leads to persistent inflammation and unbalanced host cell immune responses. Among the bacterial strains that have been identified from chronic wounds, Staphylococcus aureus is the most common strain. We previously observed that S. aureus impaired mouse cutaneous wound healing by delaying re-epithelialization. Here, we investigated the mechanism of delayed re-epithelialization caused by S. aureus infection. With the presence of S. aureus exudate, the migration of in vitro cultured human keratinocytes was significantly inhibited and connexin-43 (Cx43) was upregulated. Inhibition of keratinocyte migration by S. aureus exudate disappeared in keratinocytes where the expression of Cx43 knocked down. Protein kinase phosphorylation array showed that phosphorylation of Akt-S473 was upregulated by S. aureus exudate. In vivo study of Cx43 in S. aureus-infected murine splinted cutaneous wound model showed upregulation of Cx43 in the migrating epithelial edge by S. aureus infection. Treatment with a PI3K/Akt inhibitor reduced Cx43 expression and overcame the wound closure impairment by S. aureus infection in the mouse model. This may contribute to the development of treatment to bacterium-infected wounds.

Comparison of the Therapeutic Effect of Allogeneic and Xenogeneic Small Extracellular Vesicles in Soft Tissue Repair.

PURPOSE: Small extracellular vesicles (sEV) are a heterogeneous group of vesicles that consist of proteins, lipids and miRNA molecules derived from the cell of origin. Although xenogeneic sEV have been applied for soft tissue regeneration successfully, the regeneration effect of allogeneic and xenogeneic sEV has not been compared systematically. METHODS: Our previous study has shown that sEV derived from rat adipose tissue successfully induced neoadipose regeneration. In this study, sEV were isolated from rat adipose tissue (r-sEV-AT) and porcine adipose tissue (p-sEV-AT), the morphology, size distribution and marker proteins expression of r-sEV-AT and p-sEV-AT were characterized. Besides, the sEV/AT ratio was evaluated and compared between r-sEV-AT and p-sEV-AT. Rat adipose-derived stromal/stem cells (rASCs) and rat aorta endothelial cells (rECs) were adopted to test the cellular response to allogeneic and xenogeneic sEV-AT. The effects of allogeneic and xenogeneic sEV-AT on host cells migration and neoadipose formation were evaluated in a subcutaneous custom-designed model. A full-thickness skin wound healing model was used to further compare the ability of allogeneic and xenogeneic sEV-AT in inducing complex soft tissue regeneration. RESULTS: p-sEV-AT showed similar morphology and size distribution to r-sEV-AT. Marker proteins of sEV were detected in both r-sEV-AT and p-sEV-AT. The sEV/AT ratio of porcine was slightly higher than that of rat. The effects of r-sEV-AT and p-sEV-AT on the differentiation of rASCs and rECs showed no significant difference. When allogeneic and xenogeneic sEV-AT were subcutaneously implanted into the back of SD rats, the host cells chemotactic infiltration was observed in 1 week and neoadipose tissue formation was induced in 8 weeks; no significant difference was observed between allogeneic and xenogeneic sEV-AT. For complex soft tissue regeneration, both allogeneic and xenogeneic sEV-AT significantly promoted wound re-epithelialization, granulation tissue formation and hair follicle regeneration and then accelerated skin wound healing. CONCLUSION: Our results demonstrated that sEV derived from the same tissues of different species might be loaded with similar therapeutic substance benefitting tissue repair and regeneration, and paved the way for future research aimed at xenogeneic sEV application.

Anatomical Characteristics of Cutaneous Branches Extending From the Second Dorsal Metacarpal Artery.

BACKGROUND: A second dorsal metacarpal artery cutaneous branches flap is often used to repair skin defects in the hand. The location of the cutaneous branch of that artery is very critical for the removal of the flap. In this study, we quantitatively analyzed the origin of the cutaneous branches of the second dorsal metacarpalartery and the distribution characteristics of the radial and ulnar side to provide an anatomical basis for designing a flap. METHODS: Sixteen upper limb specimens were perfused with latex. Four specimens were infused with ethyl acetate plus plastic, and four specimens were perfused with red latex to create pellucid specimens. The origin, travel paths, and distribution of the cutaneous branches of the second dorsal metacarpal artery were anatomically observed, and we measured the length of the cutaneous branch from the midpoint of the second web space edge. We also measured the diameters and pedicle lengths of the radial and ulnar distributions of cutaneous branches of the second dorsal metacarpal artery. RESULTS: The cutaneous branches of the second dorsal metacarpal artery were mainly clustered at three positions, the second cluster point was at 43.9%, the fourth cluster point was at 61.2%, and the fifth cluster point was at 72.1%. The first cluster point was at 30.8% and the sixth cluster point was at 85.6%. The diameter and pedicle length of the sixth cluster point were the largest. There was no significant difference in the distribution of the diameters and pedicle lengths of the cutaneous branch between the radial and ulnar side. The second dorsal metacarpal artery sent out 1-2 cutaneous branches before the tendon joint, and formed a blood vessel anastomosis with other cutaneous branches located further from the tendon joint. The dorsal branch of the radial nerve in the hand extended a nerve branch at the wrist joint and traveled between the cutaneous branches of the second dorsal metacarpal artery to dominate the corresponding skin. CONCLUSION: Three clusters in the distal second dorsal metacarpal artery were selected to be the flap pedicle containing a cutaneous nerve for use in repairing a skin defect in the hand and fingers.

Effect of oral mucosal transplantation on the expression of EGF and VEGF-C during skin wound repair.

This study evaluated the effects of oral mucosal transplantation on epidermal growth factor (EGF) and vascular endothelial growth factor C (VEGF-C) in skin wound repair. Sixty-four rats were randomly separated into group A, B, C and D (16 rats in each group). The right abdomen skin was excised 1, 3, 5 and 7 days after injury, respectively. Oral mucosa of the rat tongue was transplanted to the right abdomen skin. Fourteen days after the healing of the oral mucosa graft, the rat skin full-thickness model was prepared at the transplant site (the study group) and the contralateral site (the control group). Rats in each group were anesthetized and sacrificed at 1, 3, 5 and 7 days after injury. Expression of EGF and VEGF-C in skin tissue was detected by RT-qPCR and ELISA. At 3 days, expression levels of EGF and VEGF-C mRNA and protein in skin tissue were significantly higher than those at 1 day (P<0.05). At 5 days, expression levels of EGF and VEGF-C mRNA and protein in skin tissue were significantly higher than those at 3 days (P<0.05). At 7 days, expression levels of EGF mRNA and protein in skin tissue were significantly lower than those at 5 days (P<0.05), while VEGF-C levels were significantly increased (P<0.05). Expression levels of EGF and VEGF-C mRNA and protein in the skin tissue of the study group were significantly lower than those in the control group at all days (P<0.05). EGF and VEGF-C may be involved in scar formation, and play an important role in the process of skin wound repair.

Simultaneous repair of cutaneous and subcutaneous wounds using a single suture technique.

OBJECTIVE: To describe a single suture technique for the simultaneous repair of cutaneous and subcutaneous wounds. METHOD: Skin and subcutaneous wounds of >3cm in size were repaired using a single suture technique. Different suture sizes were chosen for different wounds. Timing of suture removal was decided according to body area and wound healing status. RESULTS: A total of 78 patients were treated (41 women and 37 men). Mean age was 31.7 years (range: 14-72 years). At one month postoperatively, 56 patients attended a follow-up visit and 27 patients attended at six months postoperatively. Local infection was observed in one patient and wound dehiscence observed in two patients after suture removal. Resulting scars were similar to those of other types of suture techniques. CONCLUSION: This study describes a single suture technique for the simultaneous repair of cutaneous and subcutaneous wounds. It is easy to learn and perform. This technique reduces the risk of infection, cost and procedure time.

Preparation and properties of cellulose nanocrystals, gelatin, hyaluronic acid composite hydrogel as wound dressing.

Gelatin (GA), hyaluronic acid (HA) and cellulose nanocrystals (CNC) are promising materials for skin wound care. In this study the GA-HA-CNC hydrogels were prepared by cross-linking and freeze-drying. The composition and mechanism of GA-HA-CNC hydrogels were confirmed by FTIR. The morphology and pore size were obtained by SEM. We accessed the physical property from rheological results and swelling ratio. NIH-3T3 cells were inoculated into the hydrogels and cultured for different days, then we analyzed the cytotoxicity of the prepared hydrogels by CCK-8 methods and live/dead pictorial diagram using staining kits. FTIR revealed the combination between GA, HA and CNC was attributed to the amide bond and hydrogen bonding. SEM results showed that the drying GA-HA-CNC hydrogels were spongy, with the pore diameter about 80-120 µm. CNC significantly enhanced the property of the hydrogels and play a vital role according to the rheology and swelling results. The cells culture results showed that NIH-3T3 cells can attached to, grow, and proliferate well on the GA-HA-CNC hydrogels. In conclusion, the natural GA-HA-CNC hydrogel has great potential for the skin wound repair.

Research progress in mesenchymal stem cell-derived exosomes repairing skin tissues / 中华创伤杂志

Mesenchymal stem cells (MSCs) play an important role in skin wound repair because of their multi-directional differentiation potential, hematopoietic support and promotion of stem cell implantation, immune regulation and self-replication. Exosomes contain proteins and RNAs, which have anti-tumor immunity, angiogenesis promotion and other physiological functions. Different MSCs-derived exosomes have different mechanisms in the skin traumatic action. The author summarizes the research progress of different MSCs-derived exosomes in the field of skin tissue repair through elaborations on the traditional treatment methods for skin damage, the biological properties of exosomes, the mechanism of MSCs-derived exosomes in skin wound repair and in other diseases, providing reference for improving clinical repair.

Research progress in mesenchymal stem cell-derived exosomes repairing skin tissues / 中华创伤杂志

Mesenchymal stem cells ( MSCs) play an important role in skin wound repair because of their multi-directional differentiation potential, hematopoietic support and promotion of stem cell implantation, immune regulation and self-replication. Exosomes contain proteins and RNAs, which have anti-tumor immunity, angiogenesis promotion and other physiological functions. Different MSCs-derived exosomes have different mechanisms in the skin traumatic action. The author summarizes the research progress of different MSCs-derived exosomes in the field of skin tissue repair through elaborations on the traditional treatment methods for skin damage, the biological properties of exosomes, the mechanism of MSCs-derived exosomes in skin wound repair and in other diseases, providing reference for improving clinical repair.

Activation of NLRP3 signalling accelerates skin wound healing.

The process of skin wound healing involves the following three steps: inflammation, tissue formation and tissue remodelling. These optimal steps are required for the development of normal wound healing. Recent reports demonstrated that inflammasomes are involved in the innate immune response. In the present study, we examined whether the activation of inflammasomes affects the process of skin wound repair. The skin wound repair model was established using wild-type (WT), NACHT, LRR and PYD domains-containing protein 3 (NALP3) knockout (KO) and ASC-KO mice. The wounds were observed every other day, and changes in wound size over time were calculated using photography. Wound repair in NALP3-KO and ASC-KO mice was significantly impaired compared with WT mice. Isoliquiritigenin, an inhibitor of NALP3, decreased the rate of wound repair in WT mice. mRNA expression of pro-inflammatory cytokines in the wound sites of NALP3-KO mice was markedly decreased compared with WT mice. Treatment with adenosine triphosphate (ATP), a ligand of NALP3, upregulated the mRNA expression of pro-inflammatory cytokines at the wound site and accelerated wound healing in the WT mice. Scratch assay revealed that ATP accelerated wound closure in mouse embryonic fibroblasts from WT mice but not from NALP3-KO mice. In conclusion, the present study demonstrated that NALP3 pathway activation is involved in wound repair, and the topical use of ATP may be useful as an effective treatment for accelerating wound healing.

All hands on DE(T)C: Epithelial-resident γδ T cells respond to tissue injury.

Immunology has traditionally focused on the lymphocytes circulating among primary lymphoid organs while the large reservoir of tissue-resident T cells have received relatively less attention. In epithelia, these populations are comprised of significant, and sometimes exclusive, subsets of γδ T cells that are highly specialized in promoting tissue homeostasis. As the epithelial layers of the skin and gut are permanently exposed to the environment, they are continually subject to injury and therefore require highly efficient repair processes to maintain barrier functions. Here, we review the role of γδ T cells in promoting wound healing, a critical and complex process occurring in the skin and other barrier sites.