Skin substitutes for acute and chronic wound healing: an updated review

Quaternary ammonium grafted chitosan hydrogel with enhanced antibacterial performance as tannin acid and deferoxamine carrier to promote diabetic wound healing

The delay of diabetic wound healing puts a huge burden on the society. The key factors hindering wound healing include bacterial infection, unresolved inflammation and poorly generated blood vessels. In this paper, glycidyl trimethyl ammonium chloride (GTA) was grafted to chitosan (CS) to obtain quaternary ammonium grafted chitosan (QCS) with enhanced antibacterial performance, and then cross-linked by dialdehyde terminated poly(ethylene oxide) (PEO DA) to construct QCS/PEO DA hydrogel with tissue adhesion, biodegradation and self-healing properties. The QCS/PEO DA hydrogel is loaded with tannin acid (TA) and deferoxamine (DFO) to enhance antioxidant property and angiogenesis. At the same time, the TA and DFO loaded TA@DFO/hydrogel preserved the biocompatibility and biodegradability of chitosan. Moreover, the multifunctional hydrogel behaved excellent hemostatic properties in mice model and significantly promoted the healing efficacy of diabetic wounds. Overall, the TA@DFO/hydrogel is promising anti-infection dressing material for diabetic wound healing.

3-D bioprinted human-derived skin organoids accelerate full-thickness skin defects repair

The healing of large skin defects remains a significant challenge in clinical settings. The lack of epidermal sources, such as autologous skin grafting, limits full-thickness skin defect repair and leads to excessive scar formation. Skin organoids have the potential to generate a complete skin layer, supporting in-situ skin regeneration in the defect area. In this study, skin organoid spheres, created with human keratinocytes, fibroblasts, and endothelial cells, showed a specific structure with a stromal core surrounded by surface keratinocytes. We selected an appropriate bioink and innovatively combined an extrusion-based bioprinting technique with dual-photo source cross-linking technology to ensure the overall mechanical properties of the 3D bioprinted skin organoid. Moreover, the 3D bioprinted skin organoid was customized to match the size and shape of the wound site, facilitating convenient implantation. When applied to full-thickness skin defects in immunodeficient mice, the 3D bioprinted human-derived skin organoid significantly accelerated wound healing through in-situ regeneration, epithelialization, vascularization, and inhibition of excessive inflammation. The combination of skin organoid and 3D bioprinting technology can overcome the limitations of current skin substitutes, offering a novel treatment strategy to address large-area skin defects.

From Bank Preparation to Clinical Use of Homologous Skin Allografts in Wound Healing: A Sustainable Approach

Given progressive population ageing and the increase in the number of patients with comorbidities, the management of chronic and/or hard-to-heal wounds (HHWs) nowadays represents a common problem in many clinical settings. In these cases, standard strategies may not be sufficient. Autologous grafting represent the gold standard for permanent wound closure, but is almost never realized when the skin loss is extensive/the patient is young. The grafting of homologous skin/dermal tissue procured from cadaver donors (i.e., allografting) represents the best alternative, especially when the dermal component is lost. This request supports the activities of skin bank establishments (including donor screening, skin procurement, processing, storage, and distribution) that are regulated by specific guidelines and need to continuously meet quality standard requirements. The aim of this work is to both give specific insights of all the procedures implied in allograft preparation as well as an overview of their practical application in the treatment of different HHWs. The particular characteristics of each skin/dermal allograft released by Siena Skin Bank (cryopreserved/glycerol-preserved skin/de-epidermized dermis, acellular lyophilized de-epidermized dermis/reticular dermis) are also discussed. The exemplificative series of HHWs managed in the Dermatology Department of Siena were classified according their etiology into post-traumatic, vascular (arterial/venous/mixed/lymphatic), inflammatory, surgical, and heat/chemical burns. Globally, the clinical advantages obtained include: acceleration of healing process, pain sparing, resistance to bacterial contamination, dermal regeneration (instead of scarring), and better aesthetic-functional outcome.

3D bioprinting of fish skin-based gelatin methacryloyl (GelMA) bio-ink for use as a potential skin substitute

Gelatin methacryloyl (GelMA), typically derived from mammalian sources, has recently emerged as an ideal bio-ink for three-dimensional (3D) bioprinting. Herein, we developed a fish skin-based GelMA bio-ink for the fabrication of a 3D GelMA skin substitute with a 3D bioprinter. Several concentrations of methacrylic acid anhydride were used to fabricate GelMA, in which their physical-mechanical properties were assessed. This fish skin-based GelMA bio-ink was loaded with human adipose tissue-derived mesenchymal stromal cells (ASCs) and human platelet lysate (HPL) and then printed to obtain 3D ASCs + HPL-loaded GelMA scaffolds. Cell viability test and a preliminary investigation of its effectiveness in promoting wound closure were evaluated in a critical-sized full thickness skin defect in a rat model. The cell viability results showed that the number of ASCs increased significantly within the 3D GelMA hydrogel scaffold, indicating its biocompatibility property. In vivo results demonstrated that ASCs + HPL-loaded GelMA scaffolds could delay wound contraction, markedly enhanced collagen deposition, and promoted the formation of new blood vessels, especially at the wound edge, compared to the untreated group. Therefore, this newly fish skin-based GelMA bio-ink developed in this study has the potential to be utilized for the printing of 3D GelMA skin substitutes.

The clinical effects of artificial dermis in the treatment of skin and soft tissue defects accompanied by bone or tendon exposure

OBJECTIVE

The clinical effects of artificial dermis in treating skin and soft tissue defects accompanied by bone or tendon exposure were assessed.

APPROACH

A retrospective analysis was conducted on the clinical data of 45 cases of skin and soft tissue defects accompanied by bone or tendon exposure admitted to the trauma surgery department of Fujian Provincial Hospital between February 2018 and August 2020. They were divided into the artificial dermis and control groups. The wound was assessed using the Vancouver Scar Scale (mVSS), and the postoperative visual analogue scale (VAS) scores were recorded at 3, 6, 9, and 12 months after surgery. At the 12-month after surgery, skin sensation recovery was evaluated using the criteria of the British Medical Research Council (BMRC).

RESULTS

The cases included 26 males and 19 females, aged 50 to 85 years. All patients were followed up for an average of 13.8 months (range: 12-18 months). Compared with controls, the wound healing time of the observation group was longer (35.8 ± 10.6 vs. 28.5 ± 4.8, P = 0.007), without significant differences for the number of operations and length of hospitalization. The mVSS scores were not different between groups (Pgroup = 0.294), but the scores decreased with time (Ptime < 0.001), and the group×time interaction was significant (Pinteraction < 0.001). Similarly, the VAS scores were not different between groups (Pgroup = 0.667), but the scores decreased with time (Ptime < 0.001); the group×time interaction was not significant (Pinteraction = 0.274). At the 12-month mark following the operation, in the artificial dermis group, the MCRR score was S3+ in 23 patients, while it ranged from S0 to S3 in two patients; in the control group, S3+ was observed in 17 patients, and S0-S3 in three (P = 0.815).

CONCLUSION

Artificial dermis treatment is considered a safe and effective alternative therapy for patients with skin and soft tissue defects accompanied by bone or tendon exposure who cannot tolerate or are unwilling to undergo autologous skin flap transplantation. It offers the advantages of minimal donor site trauma, simplicity in operation, and favorable postoperative functional recovery.

The role of adipose tissue-derived stromal cells, macrophages and bioscaffolds in cutaneous wound repair

Skin healing is a complex and dynamic physiological process that follows mechanical alteration of the skin barrier. Under normal conditions, this complex process can be divided into at least three continuous and overlapping phases: an inflammatory reaction, a proliferative phase that leads to tissue reconstruction and a phase of tissue remodeling. Macrophages critically contribute to the physiological cascade for tissue repair. In fact, as the inflammatory phase progresses, macrophage gene expression gradually shifts from pro-inflammatory M1-like to pro-resolutive M2-like characteristics, which is critical for entry into the repair phase. A dysregulation in this macrophage' shift phenotype leads to the persistence of the inflammatory phase. Mesenchymal stromal cells and specifically the MSC-derived from adipose tissue (ADSCs) are more and more use to treat inflammatory diseases and several studies have demonstrated that ADSCs promote the wound healing thanks to their neoangiogenic, immunomodulant and regenerative properties. In several studies, ADSCs and macrophages have been injected directly into the wound bed, but the delivery of exogenous cells directly to the wound raise the problem of cell engraftment and preservation of pro-resolutive phenotype and viability of the cells. Complementary approaches have therefore been explored, such as the use of biomaterials enriched with therapeutic cell to improve cell survival and function. This review will present a background of the current scaffold models, using adipose derived stromal-cells and macrophage as therapeutic cells for wound healing, through a discussion on the potential impact for future applications in skin regeneration. According to the PRISMA statement, we resumed data from investigations reporting the use ADSCs and bioscaffolds and data from macrophages behavior with functional biomaterials in wound healing models. In the era of tissue engineering, functional biomaterials, that can maintain cell delivery and cellular viability, have had a profound impact on the development of dressings for the treatment of chronic wounds. Promising results have been showed in pre-clinical reports using ADSCs- and macrophages-based scaffolds to accelerate and to improve the quality of the cutaneous healing.

Acute healing outcomes in paediatric partial thickness burns using Epiprotect® and Biobrane®: A retrospective comparative study

AIM

To compare the acute healing outcomes of Biobrane® and Epiprotect® in paediatric partial thickness (PT) burns.

METHODS

All paediatric patients (age <18 years) with PT burns managed using either Biobrane® or Epiprotect® over a 5-year period at our burns unit were included. The primary outcome was time to complete healing. Secondary outcomes included adherence, infection rates, length of hospital stay, duration of acute follow-up and return to the theatre.

RESULTS

Among the 99 patients included, 38 received Epiprotect® and 61 received Biobrane®. The mean total body surface area (TBSA) was 6% (range 1%-15%) and median age was 21 months (range 5-169 months). Median time to healing in the Epiprotect® group was 19.5 days and 16 days in the Biobrane® group (P = .14). The median hospitalisation length was the same for both products (2 days, P = .85). Infection rate was lower in the Epiprotect® group (2.6% vs 16.4%, P = .048). There was no difference in adherence rate. These trends were preserved when depth sub-groups were analysed. Adherence and infection rates were not affected by post-operative antibiotics (P > .99 and P = .65, respectively) in either group. The rate of return to the theatre for further surgery was 13.2% for both products (P > .99).

CONCLUSION

Our findings demonstrate that acute healing outcomes with Epiprotect® in paediatric PT burns are comparable to those with Biobrane®, with significantly lower infection rates for Epiprotect®. These results suggest that Epiprotect® is a viable alternative to Biobrane®. Nevertheless, further prospective randomised studies are required to investigate the short- and long-term outcomes.

Guillotine Transmetatarsal Amputations With Staged Closure Promote Early Ambulation and Limb Salvage in Patients With Advanced Chronic Limb-Threatening Ischemia

PURPOSE

Transmetatarsal amputation (TMA) with primary closure has long been an option for limb salvage in patients with advanced chronic limb-threatening ischemia (CLTI) with extensive tissue loss of the forefoot. However, TMA healing and closure techniques are challenging, specifically in high-risk patients. Guillotine transmetatarsal amputations (gTMA) with staged closure may provide an alternative treatment in this population. We report long-term outcomes of such technique.

MATERIALS AND METHODS

A single-center retrospective cohort study of CLTI patients undergoing gTMA between 2017 and 2020 was performed. Limb salvage, wound healing, and survival rates were quantified using Kaplan-Meier (KM) analysis. Multivariate regression was used to identify the effect of patient characteristics on the outcomes.

RESULTS

Forty-four gTMA procedures were reviewed. Median follow-up was 381 (interquartile range [IQR], 212-539.75) days. After gTMA, 87.8% (n=36) of the patients were able to ambulate after a median interval of 2 (IQR, 1-3) days. Eventual coverage was achieved in a personalized and staged approach by using a combination of skin substitutes (88.6%, n=39) ± split thickness skin grafts (STSG, 61.4%, n=27). KM estimates for limb salvage, wound healing, and survival were 84.1%, 54.5%, and 88.6% at 1 year and 81.8%, 63.8%, and 84.1% at 2 years. Wound healing was significantly associated with STSG application (p=0.002, OR=16.5, 95% CI 2.87-94.81).

CONCLUSION

gTMA resulted in high limb salvage rates during long-term follow-up in CLTI patients. Adjunctive STSG placement may enhance wound healing at the gTMA site, thus leading to expedited wound closure. Surgeons may consider gTMA as an alternative to reduce limb loss in CLTI patients at high risk of major amputation.

CLINICAL IMPACT

Currently, the clinical presentation of CLTI is becoming more complex to deal with due to the increasing comorbidities as the society becomes older. The data shown in this article means for clinicians that when facing diffused forefoot gangrene and extensive tissue loss, limb preservation could still be considered instead of major amputation. Guillotine transmetatarsal amputations in the setting of an aggressive multidisciplinary group, can be healed by the responsibly utilization of dermal substitutes and skin grafts leading to the preservation of the extremity, allowing mobility, avoiding of sarcopenia, and decreasing frailty. This will equate to maintenance of independent living and preservation of lifespan.

NovoSorb® Biodegradable Temporizing Matrix: a novel approach for treatment of extremity avulsion injuries in children

PURPOSE

In pediatric population, large soft tissue defects occur in avulsion injuries. In addition to the challenges of primary surgical therapy, elasticity, appearance and function of the scar in children are of crucial importance, especially in the context of body growth. So far various flaps, plasties, skin grafts and dermal substitutes have become established, although infections and skin shrinkage remain challenging. In 2020, a new skin substitute material-NovoSorb® Biodegradable Temporizing Matrix (BTM)-was introduced in Europe for temporary wound closure and tissue regeneration. The aim of this study was to evaluate the value of BTM in pediatric patients.

METHODS

The study included all children treated with BTM after traumatic soft tissue defects following limb avulsion injuries between June 2021 and June 2023 at a university hospital.

RESULTS

7 patients with limb avulsion injuries were treated with BTM, 4 boys, 3 girls. Mean age was 6.5 years (2-11 years) at the time of BTM placement. 4/7 had concomitant fractures. BTM was used successfully in all cases, infection did not occur, skin shrinkage was seen in one case. Split thickness skin graft (STSG) after BTM application was performed in average after 33 days (26 to 39 days). Limitations of this study were highlighted.

CONCLUSION

BTM is a promising alternative for reconstruction of complex trauma extremity wounds in children following avulsion injuries, even in cases of concomitant bone injuries. Interpretation may be limited by sample size.

Development and characterization of ferulic acid-loaded chitosan nanoparticle embedded- hydrogel for diabetic wound delivery

Diabetic wounds present a significant global health challenge exacerbated by chronic hyperglycemia-induced oxidative stress, impeding the natural healing process. Despite various treatment strategies, diabetic foot ulceration lacks standardized therapy. Ferulic acid (FA), known for its potent antidiabetic and antioxidant properties, holds promise for diabetic wound management. However, oral administration of FA faces limitations due to rapid oxidation, stability issues, and low bioavailability. The topical application of FA-loaded chitosan nanoparticles (FA-CSNPs) has emerged as a promising approach to overcome these challenges. Here, we report the development of a sustained-release formulation of FA-CSNPs within a hydrogel matrix composed of Chitosan and gelatin. The FA-CSNPs were synthesized using the ionic gelation method andoptimized through a Central Composite Design (CCD) approach. Characterization of the optimized nanoparticles revealed spherical morphology, a particle size of 56.9 ± 2.5 nm, and an impressive entrapment efficiency of 90.3 ± 2.4 %. Subsequently, an FA-CSNPs-loaded hydrogel was formulated, incorporating chitosan as a gelling agent, gelatin to enhance mechanical properties and cell permeation, and glutaraldehyde as a cross-linker. Comprehensive characterization of the hydrogel included pH, moisture loss, porosity, swelling index, rheology, water vapor transmission rate (WVTR), SEM, TEM, invitro drug release studies, antioxidant activity, antibacterial efficacy, cell cytotoxicity, cell migration studies on L929 fibroblast cell line, and stability studies. The stability study demonstrated negligible variations in particle size, zeta potential, and entrapment efficiency over 60 days, ensuring the stable nature of nanoparticles and hydrogel. This innovative delivery approach embedded within a hydrogel matrix holds significant promise for enhancing the therapeutic efficacy of FA-CSNPs-hydrogel in diabetic wound healing applications.

Extracellular matrix-inspired biomaterials for wound healing

Diabetic foot ulcers (DFU) are a debilitating and life-threatening complication of Diabetes Mellitus. Ulceration develops from a combination of associated diabetic complications, including neuropathy, circulatory dysfunction, and repetitive trauma, and they affect approximately 19-34% of patients as a result. The severity and chronic nature of diabetic foot ulcers stems from the disruption to normal wound healing, as a result of the molecular mechanisms which underly diabetic pathophysiology. The current standard-of-care is clinically insufficient to promote healing for many DFU patients, resulting in a high frequency of recurrence and limb amputations. Biomaterial dressings, and in particular those derived from the extracellular matrix (ECM), have emerged as a promising approach for the treatment of DFU. By providing a template for cell infiltration and skin regeneration, ECM-derived biomaterials offer great hope as a treatment for DFU. A range of approaches exist for the development of ECM-derived biomaterials, including the use of purified ECM components, decellularisation and processing of donor/ animal tissues, or the use of in vitro-deposited ECM. This review discusses the development and assessment of ECM-derived biomaterials for the treatment of chronic wounds, as well as the mechanisms of action through which ECM-derived biomaterials stimulate wound healing.

Skin graft surgery and its impact on platelet counts in Iranian burn patients: a non-randomized clinical trial

BACKGROUND

Platelets are critical in maintaining homeostasis and immune response in burn patients. The concentration of platelets decreases in burn patients, and any intervention that increases serum platelet concentration can prevent serious consequences and patient death. The present study aimed to assess the impact of skin graft surgery on burn patients' platelet counts.

METHODS

In this non-randomized clinical trial, 200 burn patients were investigated. The patients were recruited from the surgical ward of Imam Khomeini Teaching Hospital during the first six months of 2021. After completing the checklist, patients underwent skin graft surgery. Blood was taken from the patients during surgery in the operating room and on the third and fifth day after the surgery to check platelets. Data analysis was conducted using SPSS software (ver. 22.0).

RESULTS

Most patients (63.5%) were male, and 73 (36.5%) were female. One hundred eighty-one patients (90.5%) had deep burns, and 19 (9.5%) had superficial burns. The mean burns percentage in the patients was 19.3 ± 15.4%, the lowest was 2%, and the highest was 90%. The most common burns were caused by flame (42%) and boiling water (30.5%). The patients' outcomes revealed that 6% gained complete recovery, 86.5% partial recovery, 2.5% showed transplant rejection, and 5% died. Mean platelet levels in deceased patients had an upward trend. The mean platelet counts of patients were elevated during surgery (289,855 ± 165,378), decreased three days after surgery (282,778 ± 317,310), and elevated again five days after surgery (330,375 ± 208,571). However, no significant difference was found between the mean platelet counts during surgery, the third and fifth days after surgery in patients undergoing skin grafts (P = 0.057).

CONCLUSIONS

This study suggests that skin graft positively increases the patient's platelets. Further studies are needed to confirm the findings and elucidate the mechanism. Iranian Registry of Clinical Trial approval code (IRCT# IRCT20131112015390N8 & 06/01/2024).

Recent advances in the adjunctive management of diabetic foot ulcer: Focus on noninvasive technologies

Diabetic foot ulcer (DFU) is one of the most costly and serious complications of diabetes. Treatment of DFU is usually challenging and new approaches are required to improve the therapeutic efficiencies. This review aims to update new and upcoming adjunctive therapies with noninvasive characterization for DFU, focusing on bioactive dressings, bioengineered tissues, mesenchymal stem cell (MSC) based therapy, platelet and cytokine-based therapy, topical oxygen therapy, and some repurposed drugs such as hypoglycemic agents, blood pressure medications, phenytoin, vitamins, and magnesium. Although the mentioned therapies may contribute to the improvement of DFU to a certain extent, most of the evidence come from clinical trials with small sample size and inconsistent selections of DFU patients. Further studies with high design quality and adequate sample sizes are necessitated. In addition, no single approach would completely correct the complex pathogenesis of DFU. Reasonable selection and combination of these techniques should be considered.

A comprehensive review of the application of 3D-bioprinting in chronic wound management

INTRODUCTION

Chronic wounds require more sophisticated care than standard wound care because they are becoming more severe as a result of diseases like diabetes. By resolving shortcomings in existing methods, 3D-bioprinting offers a viable path toward personalized, mechanically strong, and cell-stimulating wound dressings.

AREAS COVERED

This review highlights the drawbacks of traditional approaches while navigating the difficulties of managing chronic wounds. The conversation revolves around employing natural biomaterials for customized dressings, with a particular emphasis on 3D-bioprinting. A thorough understanding of the uses of 3D-printed dressings in a range of chronic wound scenarios is provided by insights into recent research and patents.

EXPERT OPINION

The expert view recognizes wounds as a historical human ailment and emphasizes the growing difficulties and expenses related to wound treatment. The expert acknowledges that 3D printing is revolutionary, but also points out that it is still in its infancy and has the potential to enhance mass production rather than replace it. The review highlights the benefits of 3D printing for wound dressings by providing instances of smart materials that improve treatment results by stimulating angiogenesis, reducing pain, and targeting particular enzymes. The expert advises taking action to convert the technology's prospective advantages into real benefits for patients, even in the face of resistance to change in the healthcare industry. It is believed that the increasing evidence from in-vivo studies is promising and represents a positive change in the treatment of chronic wounds toward sophisticated 3D-printed dressings.

Natural blackcurrant extract contained gelatin hydrogel with photothermal and antioxidant properties for infected burn wound healing

Burns represent a prevalent global health concern and are particularly susceptible to bacterial infections. Severe infections may lead to serious complications, posing a life-threatening risk. Near-infrared (NIR)-assisted photothermal antibacterial combined with antioxidant hydrogel has shown significant potential in the healing of infected wounds. However, existing photothermal agents are typically metal-based, complicated to synthesize, or pose biosafety hazards. In this study, we utilized plant-derived blackcurrant extract (B) as a natural source for both photothermal and antioxidant properties. By incorporating B into a G-O hydrogel crosslinked through Schiff base reaction between gelatin (G) and oxidized pullulan (O), the resulting G-O-B hydrogel exhibited good injectability and biocompatibility along with robust photothermal and antioxidant activities. Upon NIR irradiation, the controlled temperature (around 45-50 °C) generated by the G-O-B hydrogel resulted in rapid (10 min) and efficient killing of Staphylococcus aureus (99 %), Escherichia coli (98 %), and Pseudomonas aeruginosa (82 %). Furthermore, the G-O-B0.5 hydrogel containing 0.5 % blackcurrant extract promoted collagen deposition, angiogenesis, and accelerated burn wound closure conclusively, demonstrating that this well-designed and extract-contained hydrogel dressing holds immense potential for enhancing the healing process of bacterial-infected burn wounds.

An ADSC-loaded dermal regeneration template promotes full-thickness wound healing

Introduction

Full-thickness wounds lead to delayed wound healing and scarring. Adipose-derived stem cell (ADSC) grafting promotes wound healing and minimizes scarring, but the low efficiency of grafting has been a challenge. We hypothesized that loading ADSCs onto a clinically widely used dermal regeneration template (DRT) would improve the efficacy of ADSC grafting and promote full-thickness wound healing.

Methods

ADSCs from human adipose tissue were isolated, expanded, and labeled with a cell tracker. Labeled ADSCs were loaded onto the DRT. The viability, the location of ADSCs on the DRT, and the abundance of ADSCs in the wound area were confirmed using CCK8 and fluorescence microscopy. Full-thickness wounds were created on Bama minipigs, which were applied with sham, ADSC, DRT, and ADSC-DRT. Wounds from the four groups were collected at the indicated time and histological analysis was performed. RNA-seq analysis was also conducted to identify transcriptional differences among the four groups. The identified genes by RNA-seq were verified by qPCR. Immunohistochemistry and western blotting were used to assess collagen deposition. In vitro, the supernatant of ADSCs was used to culture fibroblasts to investigate the effect of ADSCs on fibroblast transformation into myofibroblasts.

Results

ADSCs were successfully isolated, marked, and loaded onto the DRT. The abundance of ADSCs in the wound area was significantly greater in the ADSC-DRT group than in the ADSC group. Moreover, the ADSC-DRT group exhibited better wound healing with improved re-epithelialization and denser collagen deposition than the other three groups. The RNA-seq results suggested that the application of the integrated ADSC-DRT system resulted in the differential expression of genes mainly associated with extracellular matrix remodeling. In vivo, wounds from the ADSC-DRT group exhibited an earlier increase in type III collagen deposition and alleviated scar formation. ADSCs inhibited the transformation of fibroblasts into myofibroblasts, along with increased levels of CTGF, FGF, and HGF in the supernatant of ADSCs. Wounds from the ADSC-DRT group had up-regulated expressions of CTGF, HGF, FGF, and MMP3.

Conclusion

The integral of ADSC-DRT increased the efficacy of ADSC grafting, and promoted full-thickness wound healing with better extracellular matrix remodeling and alleviated scar formation.

Advancing Tissue Damage Repair in Geriatric Diseases: Prospects of Combining Stem Cell-Derived Exosomes with Hydrogels

Geriatric diseases are a group of diseases with unique characteristics related to senility. With the rising trend of global aging, senile diseases now mainly include endocrine, cardiovascular, neurodegenerative, skeletal, and muscular diseases and cancer. Compared with younger populations, the structure and function of various cells, tissues and organs in the body of the elderly undergo a decline as they age, rendering them more susceptible to external factors and diseases, leading to serious tissue damage. Tissue damage presents a significant obstacle to the overall health and well-being of older adults, exerting a profound impact on their quality of life. Moreover, this phenomenon places an immense burden on families, society, and the healthcare system.In recent years, stem cell-derived exosomes have become a hot topic in tissue repair research. The combination of these exosomes with biomaterials allows for the preservation of their biological activity, leading to a significant improvement in their therapeutic efficacy. Among the numerous biomaterial options available, hydrogels stand out as promising candidates for loading exosomes, owing to their exceptional properties. Due to the lack of a comprehensive review on the subject matter, this review comprehensively summarizes the application and progress of combining stem cell-derived exosomes and hydrogels in promoting tissue damage repair in geriatric diseases. In addition, the challenges encountered in the field and potential prospects are presented for future advancements.

Enhancing Skin Injury Repair: Combined Application of PF-127 Hydrogel and hADSC-Exos Containing miR-148a-3p

The use of exosomes to relieve skin injuries has received considerable attention. The PluronicF-127 hydrogel (PF-127 hydrogel) is a novel biomaterial that can be used to carry biomolecules. This study sought to investigate the impact of exosomes originating from human mesenchymal stem cells (MSCs) developed from adipose tissue (hADSC-Exos) combined with a PF-127 hydrogel on tissue repair and explore the underlying mechanism using in vitro and in vivo experiments. miR-148a-3p is the most expressed microRNA (miRNA) in hADSC-Exos. We found that exosomes combined with the PF-127 hydrogel had a better efficacy than exosomes alone; moreover, miR-148a-3p knockdown lowered its efficacy. In vitro, we observed a significant increase in the tumor-like ability of HUVECs after exosome treatment, which was attenuated after miR-148a-3p knockdown. Furthermore, the effects of miR-148a-3p on hADSC-Exos were achieved through the prevention of PTEN and the triggering of phosphatidylinositol 3-kinase (PI3K)/Akt signaling. In conclusion, our results demonstrated that hADSC-Exos can promote angiogenesis and skin wound healing by delivering miR-148a-3p and have a better effect when combined with the PF-127 hydrogel, which may be an alternative strategy to promote wound healing.

Skin Substitutes and Autograft Techniques: Temporary and Permanent Coverage Solutions

Coverage of burn wounds is crucial to prevent sequalae including dehydration, wound infection, sepsis, shock, scarring, and contracture. To this end, numerous temporary and permanent options for coverage of burn wounds have been described. Temporary options for burn coverage include synthetic dressings, allografts, and xenografts. Permanent burn coverage can be achieved through skin substitutes, cultured epithelial autograft, ReCell, amnion, and autografting. Here, we aim to summarize the available options for burn coverage, as well as important considerations that must be made when choosing the best reconstructive option for a particular patient.

A bioactive composite hydrogel dressing that promotes healing of both acute and chronic diabetic skin wounds

Mesenchymal stem cell derived exosomes (MSC-Exos) demonstrate beneficial effects on wound healing via anti-inflammatory and angiogenic properties. Chitosan (CS) exhibits excellent biocompatibility and accelerates cellular migration, adhesion, and proliferation. The ions released from bioactive glass (BG) and titanium dioxide (TiO2) nanoparticles exhibit sustained angiogenic and antibacterial potency. In this study, CMCS-CEBT hydrogel was synthesized from exosomes encapsulated carboxymethyl chitosan (CMCS), chitosan nanoparticles (CS-NPs), BG, and TiO2 nanoparticles for a preliminary evaluation of its impacts on the treatment of full-thickness skin defects, diabetic wounds, and burn skin injury due to burns. In vitro analysis indicated that the hydrogel exhibits excellent cell compatibility, stimulates endothelial cell adhesion and proliferation, and presents anti-inflammatory, angiogenic, and antibacterial activities. In vivo, the composite hydrogel dressing accelerated a wound healing acceleration effect, stimulated angiogenesis, and increased collagen deposition and the expression of anti-inflammatory factors. This innovative composite hydrogel dressing as a potential clinical therapy, utilizing bioactive materials, holds promise as a potential clinical therapy that aims to facilitate the regeneration of acute and chronically damaged skin tissue.

Effect of platelet-rich plasma combined with negative pressure wound therapy in treating patients with chronic wounds: A meta-analysis

A meta-analysis was conducted to comprehensively explore the effects of platelet-rich plasma (PRP) combined with negative pressure wound therapy (NPWT) in treating patients with chronic wounds. Computer searches were conducted, from database infection to November 2023, in EMBASE, Google Scholar, Cochrane Library, PubMed, Wanfang and China National Knowledge Infrastructure databases for randomized controlled trials (RCTs) on the use of PRP combined with NPWT technology for treating chronic wounds. Two researchers independently screened the literature, extracted data and conducted quality assessments according to the inclusion and exclusion criteria. Stata 17.0 software was employed for data analysis. Overall, 18 RCTs involving 1294 patients with chronic wounds were included. The analysis revealed that, compared with NPWT alone, the use of PRP combined with NPWT technology significantly improved the healing rate (odds ratios [OR] = 1.92, 95% confidence intervals [CIs]: 1.43-2.58, p < 0.001) and total effective rate (OR = 1.31, 95% CI: 1.23-1.39, p < 0.001), and also significantly shortened the healing time of the wound (standardized mean difference = -2.01, 95% CI: -2.58 to -1.45, p < 0.001). This study indicates that the treatment of chronic wounds with PRP combined with NPWT technology can significantly enhance clinical repair effectiveness and accelerate wound healing, with a high healing rate, and is worth further promotion and practice.

Liposome-integrated hydrogel hybrids: Promising platforms for cancer therapy and tissue regeneration

Drug delivery platforms have gracefully emerged as an indispensable component of novel cancer chemotherapy, bestowing targeted drug distribution, elevating therapeutic effects, and reducing the burden of unwanted side effects. In this context, hybrid delivery systems artfully harnessing the virtues of liposomes and hydrogels bring remarkable benefits, especially for localized cancer therapy, including intensified stability, excellent amenability to hydrophobic and hydrophilic medications, controlled liberation behavior, and appropriate mucoadhesion to mucopenetration shift. Moreover, three-dimensional biocompatible liposome-integrated hydrogel networks have attracted unprecedented interest in tissue regeneration, given their tunable architecture and physicochemical properties, as well as enhanced mechanical support. This review elucidates and presents cutting-edge developments in recruiting liposome-integrated hydrogel systems for cancer treatment and tissue regeneration.

Hybrid gelatin-ascorbyl phosphate scaffolds accelerate diabetic wound healing via ROS scavenging, angiogenesis and collagen remodeling

Skin wound healing, particularly diabetic wound healing, is challenging in clinical management. Impaired wound healing is associated with persistent oxidative stress, altered inflammatory responses, unsatisfactory angiogenesis and epithelialization. Magnesium ascorbyl phosphate (MAP), which is an ascorbic acid derivative and active ingredient in cosmetics, has been reported to scavenge reactive oxygen species (ROS), and is considered a potential therapeutic agent for diabetic wounds. Herein, we report a hybrid gelatin-MAP scaffolds that can reduces oxidative stress damage, enhances angiogenesis and collagen remodeling to accelerate diabetic wound repair. Preliminary insights based on network pharmacology indicate that MAP may accelerate wound repair through multiple biological pathways, including extracellular matrix remodeling and anti-apoptosis. In vitro studies showed that the hybrid hydrogel scaffold had suitable mechanical properties, excellent biocompatibility and bioactivity. Further animal experiments demonstrated that the hydrogel accelerated full-thickness wound repair in diabetic mice (repair rate MAP vs Control=91.791±3.306 % vs 62.962±6.758 %) through antioxidant, neuroangiogenesis, collagen remodeling, and up-regulated the expression of the related factors COL-1, CD31, VEGF, and CGRP. Overall, we developed a bioactive hybrid hydrogel encapsulating MAP that synergistically promotes diabetic wound repair through multiple biological effects. This potentially integrated therapeutic scaffold may enrich future surgical approaches for treating diabetic wounds.

The transdifferentiation of human dedifferentiated fat cells into fibroblasts: An in vitro experimental pilot study

BACKGROUND

Skin grafting is a common method of treating damaged skin; however, surgical complications may arise in patients with poor health. Currently, no effective conservative treatment is available for extensive skin loss. Mature adipocytes, which constitute a substantial portion of adipose tissue, have recently emerged as a potential source of stemness. When de-lipidated, these cells exhibit fibroblast-like characteristics and the ability to redifferentiate, offering homogeneity and research utility as "dedifferentiated fat cells."

METHODS AND RESULTS

We conducted an in vitro study to induce fibroblast-like traits in the adipose tissue by transdifferentiating mature adipocytes for skin regeneration. Human subcutaneous fat tissues were isolated and purified from mature adipocytes that underwent a transformation process over 14 days of cultivation. Microscopic analysis revealed lipid degradation over time, ultimately transforming cells into fibroblast-like forms. Flow cytometry was used to verify their characteristics, highlighting markers such as CD90 and CD105 (mesenchymal stem cell markers) and CD56 and CD106 (for detecting fibroblast characteristics). Administering dedifferentiated fat cells with transforming growth factor-β at the identified optimal differentiation concentration of 5 ng/mL for a span of 14 days led to heightened expression of alpha smooth muscle actin and fibronectin, as evidenced by RNA and protein analysis. Meanwhile, functional validation through cell sorting demonstrated limited fibroblast marker expression in both treated and untreated cells after transdifferentiation by transforming growth factor-β.

CONCLUSION

Although challenges remain in achieving more effective transformation and definitive fibroblast differentiation, our trial could pave the way for a novel skin regeneration treatment strategy.

Bioengineering Skin Substitutes for Wound Management-Perspectives and Challenges

Non-healing wounds and skin losses constitute significant challenges for modern medicine and pharmacology. Conventional methods of wound treatment are effective in basic healthcare; however, they are insufficient in managing chronic wound and large skin defects, so novel, alternative methods of therapy are sought. Among the potentially innovative procedures, the use of skin substitutes may be a promising therapeutic method. Skin substitutes are a heterogeneous group of materials that are used to heal and close wounds and temporarily or permanently fulfill the functions of the skin. Classification can be based on the structure or type (biological and synthetic). Simple constructs (class I) have been widely researched over the years, and can be used in burns and ulcers. More complex substitutes (class II and III) are still studied, but these may be utilized in patients with deep skin defects. In addition, 3D bioprinting is a rapidly developing method used to create advanced skin constructs and their appendages. The aforementioned therapies represent an opportunity for treating patients with diabetic foot ulcers or deep skin burns. Despite these significant developments, further clinical trials are needed to allow the use skin substitutes in the personalized treatment of chronic wounds.

A stochastic model for topographically influenced cell migration

Migrating cells traverse a range of topographic configurations presented by the native extracellular environment to conduct their physiologic functions. It is well documented cells can modulate their behaviour in response to different topographic features, finding promising applications in biomaterial and bioimplant design. It is useful, in these areas of research, to be able to predict which topographic arrangements could be used to promote certain patterns of migration prior to laboratory experimentation. Despite a profusion of study and interest shown in these fields by experimentalists, the related modelling literature is as yet relatively sparse and tend to focus more on either cell-matrix interaction or morphological responses of cells. We propose a mathematical model for individual cell migration based on an Ornstein-Uhlenbeck process, and set out to see if the model can be used to predict migration patterns on 2-d isotropic and anisotropic topographies, whose characteristics can be broadly described as either uniform flat, uniform linear with variable ridge density or non-uniform disordered with variable feature density. Results suggest the model is capable of producing realistic patterns of migration for flat and linear topographic patterns, with calibrated output closely approximating NIH3T3 fibroblast migration behaviour derived from an experimental dataset, in which migration linearity increased with ridge density and average speed was highest at intermediate ridge densities. Exploratory results for non-uniform disordered topographies suggest cell migration patterns may adopt disorderedness present in the topography and that 'distortion' introduced to linear topographic patterns may not impede linear guidance of migration, given its magnitude is bounded within certain limits. We conclude that an Ornstein-Uhlenbeck based model for topographically influenced migration may be useful to predict patterns of migration behaviour for certain isotropic (flat) and anisotropic (linear) topographies in the NIH3T3 fibroblast cell line, but additional investigation is required to predict with confidence migration patterns for non-uniform disordered topographic arrangements.

A Model to Study Wound Healing Over Exposed Avascular Structures in Rodents With a 3D-Printed Wound Frame

BACKGROUND

Soft tissue defects with exposed avascular structures require reconstruction with well-vascularized tissues. Extensive research is ongoing to explore tissue engineered products that provide durable coverage. However, there is a lack of controlled and affordable testbeds in the preclinical setting to reflect this challenging clinical scenario. We aimed to address this gap in the literature and develop a feasible and easily reproducible model in rodents that reflects an avascular structure in the wound bed.

METHODS

We created 20 × 20 mm full thickness wounds on the dorsal skin of Lewis rats and secured 0.5-mm-thick silicone sheets of varying sizes to the wound bed. A 3D-printed wound frame was designed to isolate the wound environment. Skin graft and free flap survival along with exposure of the underlying silicone was assessed. Rats were followed for 4 weeks with weekly dressing changes and photography. Samples were retrieved at the endpoint for tissue viability and histologic analysis.

RESULTS

The total wound surface area was constant throughout the duration of the experiment in all groups and the wound frames were well tolerated. The portion of the skin graft without underlying silicone demonstrated integration with the underlying fascia and a histologically intact epidermis. Gradual necrosis of the portion of the skin graft overlying the silicone sheet was observed with varying sizes of the silicone sheet. When the size of the silicone sheet was reduced from 50% of the wound surface area, the portion surviving over the silicone sheet increased at the 4-week timepoint. The free flap provided complete coverage over the silicone sheet.

CONCLUSION

We developed a novel model of rodent wound healing to maintain the same wound size and isolate the wound environment for up to 4 weeks. This model is clinically relevant to a complex wound with an avascular structure in the wound bed. Skin grafts failed to completely cover increasing sizes of the avascular structure, whereas the free flap was able to provide viable coverage. This cost-effective model will establish an easily reproducible platform to evaluate more complex bioengineered wound coverage solutions.

Characterization and biocompatibility evaluation of acellular rat skin scaffolds for skin tissue engineering applications

Utilization of acellular scaffolds, extracellular matrix (ECM) without cell content, is growing in tissue engineering, due to their high biocompatibility, bioactivity ad mechanical support. Hence, the purpose of this research was to study the characteristics and biocompatibility of decellularized rat skin scaffolds using the osmotic shock method. First, the skin of male Wistar rats was harvested and cut into 1 × 1 cm2 pieces. Then, some of the harvested parts were subjected to the decellularization process by applying osmotic shock. Comparison of control and scaffold samples was conducted in order to assure cell elimination and ECM conservation by means of histological evaluations, quantification of biochemical factors, measurement of DNA amount, and photographing the ultrastructure of the samples by scanning electron microscopy (SEM). In order to evaluate stem cell viability and adhesion to the scaffold, adipose-derived mesenchymal stem cells (AD-MSCs) were seeded on the acellular scaffolds. Subsequently, MTT test and SEM imaging of the scaffolds containing cultured cells were applied. The findings indicated that in the decellularized scaffolds prepared by osmotic shock method, not only the cell content was removed, but also the ECM components and its ultrastructure were preserved. Also, the 99% viability and adhesion of AD-MSCs cultured on the scaffolds indicate the biocompatibility of the decellularized skin scaffold. In conclusion, decellularized rat skin scaffolds are biocompatible and appropriate scaffolds for future investigations of tissue engineering applications.

Patterns of use of advanced wound matrices in the Veterans Administration clinics

Chronic wounds are a common and costly health issue affecting millions of individuals in the United States, particularly those with underlying conditions such as diabetes, venous insufficiency, and peripheral artery disease. When standard treatments fail, advanced wound care therapies, such as skin substitutes, are often applied. However, the clinical effectiveness, indications, and comparative benefits of these therapies have not been well established. In this study, we report on the usage of both acellular and cellular, single and bilayer, natural and synthetic, dermal, and epidermal skin substitutes in a VA hospital system. We performed a retrospective chart review to understand the ordering and usage patterns of advanced wound therapies for patients with chronic wounds at the VA Northern California Health Care System. We examined types of products being recommended, categories of users recommending the products, indications for orders, and rate of repeated orders. Neuropathic, venous, or pressure ulcers were the main indications for using advanced wound matrices. Only 15.6% of patients for whom the matrices were ordered had supporting laboratory tests. Exactly 34.3% of the ordered matrices were not applied. And the use of wound matrices resulted in increased costs per patient visit of $1018-$3450. Our study sheds light on the usage patterns of these therapies in a VA healthcare facility and highlights the need for more robust evidence-based studies to determine the true benefits, efficacy, and cost-effectiveness of these innovative treatment options.

Plasma-Activated Polydimethylsiloxane Microstructured Pattern with Collagen for Improved Myoblast Cell Guidance

We focused on polydimethylsiloxane (PDMS) as a substrate for replication, micropatterning, and construction of biologically active surfaces. The novelty of this study is based on the combination of the argon plasma exposure of a micropatterned PDMS scaffold, where the plasma served as a strong tool for subsequent grafting of collagen coatings and their application as cell growth scaffolds, where the standard was significantly exceeded. As part of the scaffold design, templates with a patterned microstructure of different dimensions (50 × 50, 50 × 20, and 30 × 30 μm2) were created by photolithography followed by pattern replication on a PDMS polymer substrate. Subsequently, the prepared microstructured PDMS replicas were coated with a type I collagen layer. The sample preparation was followed by the characterization of material surface properties using various analytical techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). To evaluate the biocompatibility of the produced samples, we conducted studies on the interactions between selected polymer replicas and micro- and nanostructures and mammalian cells. Specifically, we utilized mouse myoblasts (C2C12), and our results demonstrate that we achieved excellent cell alignment in conjunction with the development of a cytocompatible surface. Consequently, the outcomes of this research contribute to an enhanced comprehension of surface properties and interactions between structured polymers and mammalian cells. The use of periodic microstructures has the potential to advance the creation of novel materials and scaffolds in tissue engineering. These materials exhibit exceptional biocompatibility and possess the capacity to promote cell adhesion and growth.

Novel approach for enhancing skin allograft survival by bioadhesive nanoparticles loaded with rapamycin

Skin graft rejection is a significant challenge in skin allografts for skin defects, particularly in extensive burn injury patients when autografts are insufficient. Enhancing the survival duration of allogeneic skin grafts can improve the success rate of subsequent autologous skin grafting, thereby promoting the therapeutic efficacy for wound healing. Rapamycin (Rapa), a potent immunosuppressant with favorable efficacy in organ transplantation, is limited by its systemic administration-associated toxicity and side effects. Therefore, addressing the short survival time of allogeneic skin grafts and minimizing the toxicity related to systemic application of immunosuppressive agents is an urgent requirement. Here, we present a topical formulation based on bioadhesive poly (lactic acid)-hyperbranched polyglycerol nanoparticles (BNPs) with surface-modified encapsulation of Rapamycin (Rapa/BNPs), applied for local immunosuppression in a murine model of allogeneic skin grafts. Our Rapa/BNPs significantly prolong nanoparticle retention, reduce infiltration of T lymphocytes and macrophages, decrease the level of pro-inflammatory cytokines and ultimately extend skin allograft survival with little systemic toxicity compared to free Rapa or Rapamycin-loaded non-bioadhesive nanoparticles (Rapa/NNPs) administration. In conclusion, Rapa/BNPs effectively deliver local immunosuppression and demonstrate potential for enhancing skin allograft survival while minimizing localized inflammation, thus potentially increasing patient survival rates for various types of skin defects.

Omentum Extracellular Matrix-Silk Fibroin Hydroscaffold Promotes Wound Healing through Vascularization and Tissue Remodeling in the Diabetic Rat Model

Nonhealing diabetic wounds are often associated with significant mortality and cause economic and clinical burdens to the healthcare system. Herein, a biomimetic hydroscaffold is developed using omentum tissue-derived decellularized-extracellular matrix (dECM) and silk fibroin (SF) proteins that associate the behavior of a collagenous fibrous scaffold and a hydrogel to reproduce all aspects of the provisional skin tissue matrix. The chemical cross-linker-free in situ gelation property of the two types of SF proteins from Bombyx mori and Antheraea assamensis ensures the adherence of dECM with surrounding tissue on the wound bed, circumventing further suturing. The physicochemical and mechanical properties of the composite hydroscaffold (SF-dECM) were thoroughly evaluated. The hydroscaffolds were found to support the growth and proliferation of human dermal fibroblasts and influence the angiogenic potential of endothelial cells under in vitro conditions. Furthermore, the healing efficacy of the composites was evaluated by generating full-thickness wounds on a streptozotocin-induced diabetic rat model. The presence of dECM components in the composite facilitated the rate of wound closure, granulation tissue formation, and re-epithelialization by providing intrinsic cues to advance the inflammatory stage and stimulating angiogenesis. Collectively, as an off-the-shelf wound dressing requiring only a single topical administration, the SF-dECM hydroscaffold is a promising, cost-effective dressing for the management of chronic diabetic wounds.

The Potential of PIP3 in Enhancing Wound Healing

Given the role of phosphatidylinositol 3,4,5-trisphosphate (PIP3) in modulating cellular processes such as proliferation, survival, and migration, we hypothesized its potential as a novel therapeutic agent for wound closure enhancement. In this study, PIP3 was examined in its free form or as a complex with cationic starch (Q-starch) as a carrier. The intracellular bioactivity and localization of free PIP3 and the Q-starch/PIP3 complexes were examined. Our results present the capability of Q-starch to form complexes with PIP3, facilitate its cellular membrane internalization, and activate intracellular paths leading to enhanced wound healing. Both free PIP3 and Q-starch/PIP3 complexes enhanced monolayer gap closure in scratch assays and induced amplified collagen production within HaCAT and BJ fibroblast cells. Western blot presented enhanced AKT activation by free or complexed PIP3 in BJ fibroblasts in which endogenous PIP3 production was pharmacologically inhibited. Furthermore, both free PIP3 and Q-starch/PIP3 complexes expedited wound closure in mice, after single or daily dermal injections into the wound margins. Free PIP3 and the Q-starch/PIP3 complexes inherently activated the AKT signaling pathway, which is responsible for crucial wound healing processes such as migration; this was also observed in wound assays in mice. PIP3 was identified as a promising molecule for enhancing wound healing, and its ability to circumvent PI3K inhibition suggests possible implications for chronic wound healing.

A potential bilayer skin substitute based on electrospun silk-elastin-like protein nanofiber membrane covered with bacterial cellulose

Skin substitutes are designed to promote wound healing by replacing extracellular matrix. Silk-elastin-like protein is a renewable extracellular matrix-like material that integrated the advantages of silk and elastin-like protein. In this study, electrospun silk-elastin-like protein (SELP) nanofiber membrane covered with bacterial cellulose (BC) was created as a potential skin substitute to mimic gradient structure of epidermis and dermis of skin. The two layers were glued together using adhesive SELP containing 3,4-dihydroxyphenylalanine (DOPA) converted from tyrosine by tyrosinase. Skin topical drugs commonly used in clinical practice can penetrate through the SELP/BC barrier, and the rate of penetration is proportional to drug concentration. BC with dense fibrous structure can act as a barrier to preserve the inner SELP layer and prevent bacterial invasion, with a blocking permeation efficiency over 99% against four species of bacteria. Cell experiments demonstrated that the reticular fibers of SELP could provide an appropriate growth environment for skin cells proliferation and adhesion, which is considered to promote tissue repair and regeneration. The promising results support this strategy to fabricate a silk-elastin-like protein-based biomaterial for skin substitutes in the clinical treatment of full skin injuries and ulcers.

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Antibiotics against Pseudomonas aeruginosa on Human Skin Cell Lines: Determination of the Highest Non-Cytotoxic Concentrations with Antibiofilm Capacity for Wound Healing Strategies

Pseudomonas aeruginosa is one of the most common microorganisms causing infections of severe skin wounds. Antibiotic or antiseptic treatments are crucial to prevent and curb these infections. Antiseptics have been reported to be cytotoxic to skin cells and few studies evaluate the impact of commonly used antibiotics. This study evaluates how clinical antibiotics affect skin cells' viability, proliferation, migration, and cytokine secretion and defines the highest non-cytotoxic concentrations that maintain antibacterial activity. Cell proliferation, viability, and migration were evaluated on cell monolayers. Cytokines related to the wound healing process were determined. The minimum inhibitory concentrations and the impact on bacterial biofilm were assessed. Results showed that 0.02 mg/mL ciprofloxacin and 1 mg/mL meropenem are the highest non-cytotoxic concentrations for fibroblasts and keratinocytes while 1.25 mg/mL amikacin and 0.034 mg/mL colistin do not affect fibroblasts' viability and cytokine secretion but have an impact on keratinocytes. These concentrations are above the minimum inhibitory concentration but only amikacin could eradicate the biofilm. For the other antibiotics, cytotoxic concentrations are needed to eradicate the biofilm. Combinations with colistin at non-cytotoxic concentrations effectively eliminate the biofilm. These results provide information about the concentrations required when administering topical antibiotic treatments on skin lesions, and how these antibiotics affect wound management therapies. This study set the basis for the development of novel antibacterial wound healing strategies such as antibiotic artificial skin substitutes.

Antibacterial functionalization of calfskin bioremediation film

Decellularized calfskins are a well-established skin substitute that retains the dermal tissue's spatial structure, facilitating skin regeneration, and is already available in the market. However, their mechanical properties can change with degradation, leading to tearing at the suture. Moreover, decellularized calfskins do not possess inherent antimicrobial abilities, which can lead to wound infection and further injury during the healing process. With the objectives of supporting the clinical use of decellularized calfskins, minimizing the probability of decellularized calfskin fracture and damage during usage, and improving their anti-infective properties, this study utilized a post-loading method to load gentamicin sulfate onto the decellularized calfskin to functionalize it for antimicrobial purposes. In addition, the mechanical and physicochemical properties of the drug-carrying film were investigated to see if they could meet the clinical requirements. The results revealed that vancomycin sulfate could be loaded onto the decellularized calfskin without affecting collagen. The tensile strength of the drug-loaded membrane was determined to be in the range of 5.53-29.25 MPa, meeting the clinical requirements. Thermal analysis and pH analysis experiments demonstrated that the drug-loaded membrane did not undergo thermal denaturation or decomposition during skin repair and remained within the normal pH range of the skin, avoiding significant fluctuations in wound pH.

Monitoring angiogenesis in skin autografts using photoacoustic microscopy

BACKGROUND

Skin autografts have been broadly used to manage the skin and soft tissue defects. It is important for surgeons to assess the vitality of skin autografts via observing the angiogenesis. However, there is lack of reliable approach for giving the quantitative angiogenesis information on the skin autografts. Recently, photoacoustic microscopy imaging has attracted much attention based on its good performance in angiography.

METHODS

In this study, we aim to monitor angiogenesis in skin autografts via PAM, and further verify its clinical potential for the early prediction of skin autografts clinical outcome.

RESULTS AND CONCLUSIONS

The results indicate that PAM is a feasible, precise, high-resolution, noninvasive technique for the early prediction of necrosis of skin autografts via monitoring the angiogenesis, providing a promising tool for surgeons to use this surgical technology.

Artificial dermis combined with split-thickness skin autograft in the treatment of hand thermal compression wounds: a single center case-control study

Objective

To explore the clinical effect of artificial dermis combined with split-thickness skin autograft in treating hand thermal compression wounds.

Methods

Forty-two patients in our hospital from January 2016 to October 2022 with thermal compression wounds were divided into two groups. The survival rate of autologous skin grafts seven days after skin grafting, the number of operations, total hospital stay, total hospitalization cost, and bacterial culture results of secretions were recorded. The visual analog scale was used to evaluate the wound pain. The condition of skin graft rupture was recorded and the scar status of the donor site was evaluated by the Vancouver Scar Scale.

Results

It showed combination of artificial dermis, split-thickness skin autograft, and vacuum sealing drainage improves the treatment of hand thermal compression wounds by enhancing the survival rate of skin grafting (95.24% > 66.67%), reducing the number of operations (P < 0.001), relieving wound pain (P < 0.001), effectively controlling wound infection (4.76% < 9.52%), and reducing the skin graft rupture rate after surgery (4.8% < 28.6%). There was no evident scar hyperplasia in the donor (P = 0.003) and skin graft areas (P < 0.001), which had a good recovery of hand function (P = 0.037); however, this treatment strategy may prolong the hospital stay (P = 0.030) and increase the total hospitalization cost (P = 0.030).

Conclusion

The composite transplantation of artificial dermis and split-thickness skin combined with the VSD significantly improves treatment and aesthetic outcomes in patients with thermal compression wounds to the hand, which is worth promoting and applying in clinical practice.

UV-polymerizable methacrylated gelatin (GelMA)-based hydrogel containing tannic acids for wound healing

Gelatin-based photopolymerizable methacrylate hydrogel (GelMA) is a promising biomaterial for in situ drug delivery, while aqueous extract of Punica granatum (AEPG) peel fruit rich in gallic acid and ellagic acid is used to improve wound healing. The aim of this study was to develop and analyze the healing properties of GelMA containing AEPG, gallic acid, or ellagic acid in a rodent model. GelMA hydrogels containing 5% AEPG (GelMA-PG), 1.6% gallic acid (GelMA-GA), or 2.1% ellagic acid (GelMA-EA) were produced and their mechanical properties, enzymatic degradation, and thermogravimetric profile determined. Wound closure rates, healing histological grading, and immunohistochemical counts of myofibroblasts were assessed over time. The swelling of hydrogels varied between 50 and 90%, and GelMA exhibited a higher swelling than the other groups. The GPG samples showed higher compression and Young's moduli than GelMA, GGA, and GAE. All samples degraded around 95% in 48 h. GPG and GGA significantly accelerated wound closure, improved collagenization, increased histological grading, and hastened myofibroblast differentiation in comparison to the control, GelMA, and GEA. GelMA containing AEPG (GPG) improved wound healing, and although gallic acid is the major responsible for such biological activity, a potential synergic effect played by other polyphenols present in the extract is evident.

Development of a Self-Assembled Dermal Substitute from Human Fibroblasts Using Long-term Three-Dimensional Culture

Skin substitutes have emerged as an alternative to autografts for the treatment of skin defects. Among them, scaffold-based dermal substitutes have been extensively studied; however, they have certain limitations, such as delayed vascularization, limited elasticity, and the inability to achieve permanent engraftment. Self-assembled, cell-based dermal substitutes are a promising alternative that may overcome these shortcomings but have not yet been developed. In this study, we successfully developed a cell-based dermal substitute (cultured dermis) through the long-term culture of human dermal fibroblasts using the net-mold method, which enables three-dimensional cell culture without the use of a scaffold. Spheroids prepared from human dermal fibroblasts were poured into a net-shaped mold and cultured for 2, 4, or 6 months. The dry weight, tensile strength, collagen and glycosaminoglycan levels, and cell proliferation capacity were assessed and compared among the 2-, 4-, and 6-month culture periods. We found that collagen and glycosaminoglycan levels decreased over time, while the dry weight remained unchanged. Tensile strength increased at 4 months, suggesting that remodeling had progressed. In addition, the cell proliferation capacity was maintained, even after a 6-month culture period. Unexpectedly, the internal part of the cultured dermis became fragile, resulting in the division of the cultured dermis into two collagen-rich tissues, each of which had a thickness of 400 μm and sufficient strength to be sutured during in vivo analysis. The divided 4-month cultured dermis was transplanted to skin defects of immunocompromised mice and its wound healing effects were compared to those of a clinically available collagen-based artificial dermis. The cultured dermis promoted epithelialization and angiogenesis more effectively than the collagen-based artificial dermis. Although further improvements are needed, such as the shortening of the culture period and increasing the size of the cultured dermis, we believe that the cultured dermis presented in this study has the potential to be an innovative material for permanent skin coverage.

Cell-loaded genipin cross-linked collagen/gelatin skin substitute adorned with zinc-doped bioactive glass-ceramic for cutaneous wound regeneration

An optimal tissue-engineered dermal substitute should possess biocompatibility and cell adhesion conduction to facilitate fibroblast and keratinocyte infiltration and proliferation, as well as angiogenesis potential to escalate wound healing. Zinc was doped to bioactive glass-ceramic (Zn-BGC) to promote biocompatibility and angiogenesis properties. Zn-BGC was then incorporated into a collagen (Col) and gelatin (Gel) porous scaffold. The bioactive porous bionanocomposite exhibited biocompatibility along with improved cell attachment and proliferation. Scaffolds including Col-Gel/Zn-BGC with or without mouse embryonic fibroblasts were applied on full-thickness skin wounds on the BALB/c mice to assess their wound healing potential in vivo. The results indicated that the biodegradation rate of the Col-Gel/Zn-BGC nanocomposites was comparable to the rate of skin tissue regeneration in vivo. Macroscopic wound healing results showed that Col-Gel/Zn-BGC loaded with mouse embryonic fibroblast possesses the smallest wound size, indicating the fastest healing process. Histopathological evaluations displayed that the optimal wound regeneration was observed in Col-Gel/Zn-BGC nanocomposites loaded with mouse embryonic fibroblasts indicated by epithelialization and angiogenesis; besides the number of fibroblasts and hair follicles was increased. The bioactive nanocomposite scaffold of Col-Gel containing Zn-BGC nanoparticles loaded with mouse embryonic fibroblasts can be employed as a desirable skin substitute to ameliorate cutaneous wound regeneration.

Biomaterials derived from hard palate mucosa for tissue engineering and regenerative medicine

Autologous materials have superior biosafety and are widely used in clinical practice. Due to its excellent trauma-healing ability, the hard palate mucosa (HPM) has become a hot spot for autologous donor area research. Multiple studies have conducted an in-depth analysis of the healing ability of the HPM at the cellular and molecular levels. In addition, the HPM has good maneuverability as a donor area for soft tissue grafts, and researchers have isolated various specific mesenchymal stem cells (MSCs) from HPM. Free soft tissue grafts obtained from the HPM have been widely used in the clinic and have played an essential role in dentistry, eyelid reconstruction, and the repair of other specific soft tissue defects. This article reviews the advantages of HPM as a donor area and its related mechanisms, classes of HPM-derived biomaterials, the current status of clinical applications, challenges, and future development directions.

Skin substitutes as treatment for chronic wounds: current and future directions

Chronic wounds such as diabetic foot ulcers and venous leg ulcers place a significant burden on the healthcare system and in some cases, have 5-year mortality rates comparable to cancer. They negatively impact patients' quality of life due to pain, odor, decreased mobility, and social isolation. Skin substitutes are an advanced therapy recommended for wounds that fail to show decrease in size with standard care. The choice of substitute used should be based on evidence, which often differs based on wound etiology. There are more than 75 skin substitutes currently available, and that number is rising. In this review, we discuss current management and future directions of chronic wounds while providing a review of available randomized control trial data for various skin substitutes.

Placental-Derived Biomaterials and Their Application to Wound Healing: A Review

Chronic wounds are associated with considerable patient morbidity and present a significant economic burden to the healthcare system. Often, chronic wounds are in a state of persistent inflammation and unable to progress to the next phase of wound healing. Placental-derived biomaterials are recognized for their biocompatibility, biodegradability, angiogenic, anti-inflammatory, antimicrobial, antifibrotic, immunomodulatory, and immune privileged properties. As such, placental-derived biomaterials have been used in wound management for more than a century. Placental-derived scaffolds are composed of extracellular matrix (ECM) that can mimic the native tissue, creating a reparative environment to promote ECM remodeling, cell migration, proliferation, and differentiation. Reliable evidence exists throughout the literature to support the safety and effectiveness of placental-derived biomaterials in wound healing. However, differences in source (i.e., anatomical regions of the placenta), preservation techniques, decellularization status, design, and clinical application have not been fully evaluated. This review provides an overview of wound healing and placental-derived biomaterials, summarizes the clinical results of placental-derived scaffolds in wound healing, and suggests directions for future work.

Wound healing strategies based on nanoparticles incorporated in hydrogel wound patches

The intricate, tightly controlled mechanism of wound healing that is a vital physiological mechanism is essential to maintaining the skin's natural barrier function. Numerous studies have focused on wound healing as it is a massive burden on the healthcare system. Wound repair is a complicated process with various cell types and microenvironment conditions. In wound healing studies, novel therapeutic approaches have been proposed to deliver an effective treatment. Nanoparticle-based materials are preferred due to their antibacterial activity, biocompatibility, and increased mechanical strength in wound healing. They can be divided into six main groups: metal NPs, ceramic NPs, polymer NPs, self-assembled NPs, composite NPs, and nanoparticle-loaded hydrogels. Each group shows several advantages and disadvantages, and which material will be used depends on the type, depth, and area of the wound. Better wound care/healing techniques are now possible, thanks to the development of wound healing strategies based on these materials, which mimic the extracellular matrix (ECM) microenvironment of the wound. Bearing this in mind, here we reviewed current studies on which NPs have been used in wound healing and how this strategy has become a key biotechnological procedure to treat skin infections and wounds.

Revisiting the Role of Amniotic Membrane Dressing in Acute Large Traumatic Wounds: A Randomized Feasibility Study at a Level 1 Trauma Centre

Introduction

Acute large traumatic wounds require temporary dressing prior to the definitive soft tissue reconstruction, as the physiological derangement during the immediate postinjury period delays the definitive surgical intervention. Selecting an ideal dressing material from numerous available synthetic dressings and skin substitutes poses a challenge. Although amniotic membrane (AM) scaffold has a definitive role in promoting wound healing in burns and chronic wounds, however, its efficacy in acute large traumatic wound is lacking. The present trial aimed to evaluate the safety and efficacy of AM in wound bed preparation before the definitive soft-tissue reconstruction in acute large traumatic wounds.

Methods

Sixty patients with acute large traumatic wounds (>10 cm × 10 cm) were divided into two groups (conventional dressing and AM dressing) using simple mixed block randomization. Wounds were assessed using the Bates Jensen Score at various timelines for the signs of early wound healing. The primary outcome was to evaluate the time taken for the wound bed preparation for definitive soft-tissue reconstruction. The secondary outcome was the pain assessment and complications, if any.

Results

There was significant reduction in the wound exudate as well as peripheral tissue edema in the intervention group (P = 0.01). AM dressing was significantly less painful (P = 0.01). The incidence of wound infection and need for debridement was decreased in the intervention group. However, the time interval to definitive soft-tissue coverage was statistically insignificant and comparable in both the groups. No adverse reactions were seen in either group.

Conclusion

AM dressings are safe and efficacious with significant reduction in wound exudates and peripheral edema. However, these dressings do not hasten the wound maturation as compared to conventional dressings. AM dressings can be used as a less painful alternative to conventional dressing in the management of large acute posttraumatic wounds.