The Application of Decellularized Adipose Tissue Promotes Wound Healing

SOX family transcription factors as therapeutic targets in wound healing: A comprehensive review

The SOX family plays a vital role in determining the fate of cells and has garnered attention in the fields of cancer research and regenerative medicine. It also shows promise in the study of wound healing, as it actively participates in the healing processes of various tissues such as skin, fractures, tendons, and the cornea. However, our understanding of the mechanisms behind the SOX family's involvement in wound healing is limited compared to its role in cancer. Gaining insight into its role, distribution, interaction with other factors, and modifications in traumatized tissues could provide valuable new knowledge about wound healing. Based on current research, SOX2, SOX7, and SOX9 are the most promising members of the SOX family for future interventions in wound healing. SOX2 and SOX9 promote the renewal of cells, while SOX7 enhances the microvascular environment. The SOX family holds significant potential for advancing wound healing research. This article provides a comprehensive review of the latest research advancements and therapeutic tools related to the SOX family in wound healing, as well as the potential benefits and challenges of targeting the SOX family for wound treatment.

Delivery of adipose-derived growth factors from heparinized adipose acellular matrix accelerates wound healing

Dermal white adipocytes are closely associated with skin homeostasis and wound healing. However, it has not been fully investigated whether adipose-derived products improve wound healing. Here, we obtained adipose acellular matrix (AAM) and adipose-derived growth factors (ADGFs) from human adipose tissue and fabricated an ADGF-loaded AAM via surface modification with heparin. The product, HEP-ADGF-AAM, contained an adipose-derived scaffold and released ADGFs in a controlled fashion. To test its efficacy in promoting wound healing, mice with full thickness wound received three different treatments: HEP-ADGF-AAM, AAM and ADM. Control mice received no further treatments. Among these treatments, HEP-ADGF-AAM best improved wound healing. It induced adipogenesis in situ after in vivo implantation and provided an adipogenic microenvironment for wounds by releasing ADGFs. HEP-ADGF-AAM not only induced adipocyte regeneration, but also enhanced fibroblast migration, promoted vessel formation, accelerated wound closure, and enhanced wound epithelialization. Moreover, there was a close interaction between HEP-ADGF-AAM and the wound bed, and collagen was turned over in HEP-ADGF-AAM. These results show that HEP-ADGF-AAM might substantially improve re-epithelialization, angiogenesis, and skin appendage regeneration, and is thus a promising therapeutic biomaterial for skin wound healing.

Recent advances in decellularized biomaterials for wound healing

The skin is one of the most essential organs in the human body, interacting with the external environment and shielding the body from diseases and excessive water loss. Thus, the loss of the integrity of large portions of the skin due to injury and illness may lead to significant disabilities and even death. Decellularized biomaterials derived from the extracellular matrix of tissues and organs are natural biomaterials with large quantities of bioactive macromolecules and peptides, which possess excellent physical structures and sophisticated biomolecules, and thus, promote wound healing and skin regeneration. Here, we highlighted the applications of decellularized materials in wound repair. First, the wound-healing process was reviewed. Second, we elucidated the mechanisms of several extracellular matrix constitutes in facilitating wound healing. Third, the major categories of decellularized materials in the treatment of cutaneous wounds in numerous preclinical models and over decades of clinical practice were elaborated. Finally, we discussed the current hurdles in the field and anticipated the future challenges and novel avenues for research on decellularized biomaterials-based wound treatment.

Decellularized extracellular matrix (d-ECM): the key role of the inflammatory process in pre-regeneration after implantation

Clinical medicine is encountering the challenge of repairing soft-tissue defects. Currently, natural and synthetic materials have been developed as natural scaffolds. Among them, the decellularized extracellular matrix (d-ECM) can achieve tissue remodeling following injury and, thus, replace defects due to its advantages of the extensiveness of the source and excellent biological and mechanical properties. However, by analyzing the existing decellularization techniques, we found that different preparation methods directly affect the residual components of the d-ECM, and further have different effects on inflammation and regeneration of soft tissues. Therefore, we analyzed the role of different residual components of the d-ECM after decellularization. Then, we explored the inflammatory process and immune cells in an attempt to understand the mechanisms and causes of tissue degeneration and regeneration after transplantation. In this paper, we summarize the current studies related to updated protocols for the preparation of the d-ECM, biogenic and exogenous residual substances, inflammation, and immune cells influencing the fate of the d-ECM.

Adipose-derived stem cells applied in skin diseases, wound healing and skin defects: a review

Adipose tissue presents a comparably easy source for obtaining stem cells, and more studies are increasingly investigating the therapeutic potential of adipose-derived stem cells. Wound healing, especially in chronic wounds, and treatment of skin diseases are some of the fields investigated. In this narrative review, the authors give an overview of some of the latest studies concerning wound healing as well as treatment of several skin diseases and concentrate on the different forms of application of adipose-derived stem cells.

Vessel-Derived Decellularized Extracellular Matrices (VdECM): Novel Bio-Engineered Materials for the Wound Healing

BACKGROUND

Decellularized extracellular matrix (dECM) is a non-cellular scaffold with various functions in tissue engineering and regenerative medicine. Elastin is related to tissue elasticity and scarless wound healing, abundantly found in lung and blood vessel tissues. We studied the characteristics of blood vessel-derived dECM (VdECM) and its effect in wound healing.

METHODS

VdECM was prepared from porcine blood vessel tissue. Weight percentages of elastin of VdECM and atelocollagen were analyzed. Migratory potential of VdECM was tested by scratch assay. VdECM in hydrogel form was microscopically examined, tested for fibroblast proliferation, and examined for L/D staining. Cytokine array of various growth factors in adipocyte-derived mesenchymal stem cell (ASC) media with VdECM was done. Animal wound model showed the wound healing effect of VdECM hydrogel in comparison to other topical agents.

RESULTS

VdECM contained 6.7 times more elastin than atelocollagen per unit weight. Microscopic view of 0.35% VdECM hydrogel showed consistent distribution. Compared to 3% atelocollagen, 0.35% VdECM showed superior results in fibroblast migration. Fluorescent microscopic findings of L/D assay had highest percentage of cell survival in 1% VdECM compared to atelocollagen. Growth factor expression was drastically amplified when VdECM was added to ASC media. In the animal study model, epithelialization rate in the VdECM group was higher than that of control, oxytetracycline, and epidermal growth factor ointments.

CONCLUSION

VdECM contains a high ratio of elastin to collagen and amplifies expressions of many growth factors. It promotes fibroblast migration, proliferation, and survival, and epithelialization comparable to other topical agents.

Sodium alginate/gelatin hydrogels loaded with adipose-derived mesenchymal stem cells promote wound healing in diabetic rats

BACKGROUND

Chronic refractory wounds are a common complication in diabetic patients. Adipose-derived mesenchymal stem cells (ASCs) have been shown to play an essential role in diabetic wound repair.

AIMS

To determine whether a composite of ASCs and sodium alginate/gelatin (Gel-Al) hydrogel can promote diabetic wound healing.

METHODS

Full-thickness cutaneous wounds were created in streptozotocin-induced diabetic rats prior to treatment with Gel-Al hydrogels loaded with ASCs. Hydrogel biocompatibility and wound healing were analyzed. Hematoxylin and eosin staining, Masson staining, immunofluorescence, enzyme-linked immunosorbent assays (ELISA), and quantitative real-time PCR were performed for the assessment of cellular responses.

RESULTS

Compared to the control group or Gel-Al alone group, the combination of Gel-Al and ASCs promoted wound closure, facilitated granulation tissue regeneration and collagen deposition, and upregulated the expression of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and endothelial cell marker CD31. Moreover, the combination of Gel-Al and ASCs decreased interleukin-6 (IL-6) and interleukin-1β (IL-1β) expression, increased transforming growth factor beta1 (TGFβ1), interleukin-10 (IL-10), interleukin-4 (IL-4) and interleukin-13 (IL-13) expression, and increased M2 macrophage polarization.

CONCLUSIONS

Gel-Al hydrogels loaded with ASCs accelerate diabetic wound healing. The Gel-Al hydrogel-based ASC system therefore represents an innovative therapeutic strategy for diabetic wound repair.

Adjusting the stiffness of a cell-free hydrogel system based on tissue-specific extracellular matrix to optimize adipose tissue regeneration

Background

Large-area soft tissue defects are challenging to reconstruct. Clinical treatment methods are hampered by problems associated with injury to the donor site and the requirement for multiple surgical procedures. Although the advent of decellularized adipose tissue (DAT) offers a new solution to these problems, optimal tissue regeneration efficiency cannot be achieved because the stiffness of DAT cannot be altered in vivo by adjusting its concentration. This study aimed to improve the efficiency of adipose regeneration by physically altering the stiffness of DAT to better repair large-volume soft tissue defects.

Methods

In this study, we formed three different cell-free hydrogel systems by physically cross-linking DAT with different concentrations of methyl cellulose (MC; 0.05, 0.075 and 0.10 g/ml). The stiffness of the cell-free hydrogel system could be regulated by altering the concentration of MC, and all three cell-free hydrogel systems were injectable and moldable. Subsequently, the cell-free hydrogel systems were grafted on the backs of nude mice. Histological, immunofluorescence and gene expression analyses of adipogenesis of the grafts were performed on days 3, 7, 10, 14, 21 and 30.

Results

The migration of adipose-derived stem cells (ASCs) and vascularization were higher in the 0.10 g/ml group than in the 0.05 and 0.075 g/ml groups on days 7, 14 and 30. Notably, on days 7, 14 and 30, the adipogenesis of ASCs and adipose regeneration were significantly higher in the 0.075 g/ml group than in the 0.05 g/ml group (p < 0.01 or p < 0.001) and 0.10 g/ml group (p < 0.05 or p < 0.001).

Conclusion

Adjusting the stiffness of DAT via physical cross-linking with MC can effectively promote adipose regeneration, which is of great significance to the development of methods for the effective repair and reconstruction of large-volume soft tissue defects.

Analysis of DAT Combined with the VSD Technique in Wound Repair of Rats and Its Effect on Inflammatory Factors

The clinical efficacy of decellularized adipose tissue (DAT) combined with vacuum sealing drainage (VSD) in the treatment of wound healing in rats is investigated, and the changes of inflammatory factors are analyzed. The tissue defect model of SD (Sprague-Dawley) rats is established and divided into the combined group (n = 12) and the control group (n = 12) according to different treatment methods. The control group is treated with a single VSD technique, and the combined group is treated with DAT on the basis of the control group. The wound healing time of the two groups is observed. Wound tissue is collected 1 day, 10 days, 20 days, and 30 days after treatment, and neutrophil infiltration is observed by HE (hematoxylin-eosin) staining. The expression changes of IL-6 and IL-13 at each time point before and after treatment are compared. Histological observation shows that the cell infiltration is reduced in both groups, and the wound repair in the combined group is better than that in the control group. The experimental results show that the DAT combined with the VSD technique can further speed up wound healing and reduce inflammation in rats.

Macrophage-derived apoptotic vesicles regulate fate commitment of mesenchymal stem cells via miR155

BACKGROUND

In tissue engineering, mesenchymal stem cells (MSCs) are common seed cells because of abundant sources, strong proliferation ability and immunomodulatory function. Numerous researches have demonstrated that MSC-macrophage crosstalk played a key role in the tissue engineering. Macrophages could regulate the differentiation of MSCs via different molecular mechanisms, including extracellular vesicles. Apoptotic macrophages could generate large amounts of apoptotic vesicles (apoVs). ApoVs are rich in proteins, RNA (microRNAs, mRNAs, ncRNAs, etc.) and lipids, and are a key intercellular communication mediator that can exert different regulatory effects on recipient cells. MiRNAs account for about half of the total RNAs of extracellular vesicles, and play important roles in biological processes such as cell proliferation and differentiation, whereas the functions of macrophage-derived apoVs remain largely unknown. There was no research to clarify the role of macrophage-derived apoVs in MSC fate choices. In this study, we aimed to characterize macrophage-derived apoVs, and investigate the roles of macrophage-derived apoVs in the fate commitment of MSCs.

METHODS

We characterized macrophage-derived apoVs, and investigated their role in MSC osteogenesis and adipogenesis in vitro and in vivo. Furthermore, we performed microRNA loss- and gain-of-function experiments and western blot to determine the molecular mechanism.

RESULTS

Macrophages could produce a large number of apoVs after apoptosis. MSCs could uptake apoVs. Then, we found that macrophage-derived apoVs inhibited osteogenesis and promoted adipogenesis of MSCs in vitro and in vivo. In mechanism, apoVs were enriched for microRNA155 (miR155), and apoVs regulated osteogenesis and adipogenesis of MSCs by delivering miR155. Besides, miR155 regulated osteogenesis and adipogenesis of MSCs cultured with macrophage-derived apoVs via the SMAD2 signaling pathway.

CONCLUSIONS

Macrophage-derived apoVs could regulate the osteogenesis and adipogenesis of MSCs through delivering miR155, which provided novel insights for MSC-mediated tissue engineering.

Research progress of natural tissue-derived hydrogels for tissue repair and reconstruction

There are many different grafts to repair damaged tissue. Various types of biological scaffolds, including films, fibers, microspheres, and hydrogels, can be used for tissue repair. A hydrogel, which is composed a natural or synthetic polymer network with high water absorption capacity, can provide a microenvironment closely resembling the extracellular matrix (ECM) of natural tissues to stimulate cell adhesion, proliferation, and differentiation. It has been shown to have great application potential in the field of tissue repair and regeneration. Hydrogels derived from natural tissues retain a variety of proteins and growth factors in optimal proportions, which is beneficial for the regeneration of specific tissues. This article reviews the latest research advances in the field of hydrogels from a variety of natural tissue sources, including bone tissue, blood vessels, nerve tissue, adipose tissue, skin tissue, and muscle tissue, including preparation methods, advantages, and applications in tissue engineering and regenerative medicine. Finally, it summarizes and discusses the challenges faced by natural tissue-derived hydrogels used in tissue repair, as well as future research and application directions.

Metal Ion Releasing Gold Nanoparticles for Improving Therapeutic Efficiency of Tumor Targeted Photothermal Therapy

BACKGROUND

Owing to the tumor-targeted migration capacity of human mesenchymal stem cells (hMSCs), they have been combined with nanoparticles for photothermal therapy. However, the low viability of hMSCs following transplantation remains a problem. Here, we developed iron (Fe) ion-releasing gold (Au) nanoparticles (IIAuNPs) for advanced tumor-targeted photothermal therapy using hMSCs.

METHODS

IIAuNPs were designed to undergo degradation under low pH conditions, such as the endosomal microenvironment, for Fe ion release in hMSCs. After evaluating the properties of IIAuNP, the IIAuNP concentration for treating hMSCs was optimized in terms of cytotoxicity. In vitro cell migration and antiapoptotic factor secretion were observed in hMSCs. Additionally, IIAuNPs-treated hMSCs were intravenously injected into tumor-bearing mice, and enhanced tumor targeting based on improved cell viability and cell migration was evaluated. Three days after the injection, the mice were irradiated with 660 nm laser to confirm the enhanced photothermal effect.

RESULTS

In vitro studies revealed that treating hMSCs with an optimum concentration of IIAuNPs enhanced cell migration and anti-apoptotic gene expression through intracellular Fe ion delivery. The viability of hMSCs under hypoxic cell culture conditions that mimic the in vivo microenvironment was also improved when hMSCs were treated with IIAuNPs, compared to hMSCs without IIAuNPs treatment. IIAuNPs-treated hMSCs showed significantly enhanced tumor-targeting efficiency and subsequent photothermal effect compared to hMSCs without IIAuNP treatment.

CONCLUSION

Our results suggest that our metal-ion-releasing photothermal nanoparticles may provide a promising platform for future photothermal therapies and related applications.

Therapeutic Efficacy of Artificial Skin Produced by 3D Bioprinting

The skin protects the body from external barriers. Certain limitations exist in the development of technologies to rapidly prepare skin substitutes that are therapeutically effective in surgeries involving extensive burns and skin transplantation. Herein, we fabricated a structure similar to the skin layer by using skin-derived decellularized extracellular matrix (dECM) with bioink, keratinocytes, and fibroblasts using 3D-printing technology. The therapeutic effects of the produced skin were analyzed using a chimney model that mimicked the human wound-healing process. The 3D-printed skin substitutes exhibited rapid re-epithelialization and superior tissue regeneration effects compared to the control group. These results are expected to aid the development of technologies that can provide customized skin-replacement tissues produced easily and quickly via 3D-printing technology to patients.