Effect of human Wharton's jelly mesenchymal stem cell paracrine signaling on keloid fibroblasts

Stem cell-based therapy for fibrotic diseases: mechanisms and pathways

Fibrosis is a pathological process, that could result in permanent scarring and impairment of the physiological function of the affected organ; this condition which is categorized under the term organ failure could affect various organs in different situations. The involvement of the major organs, such as the lungs, liver, kidney, heart, and skin, is associated with a high rate of morbidity and mortality across the world. Fibrotic disorders encompass a broad range of complications and could be traced to various illnesses and impairments; these could range from simple skin scars with beauty issues to severe rheumatologic or inflammatory disorders such as systemic sclerosis as well as idiopathic pulmonary fibrosis. Besides, the overactivation of immune responses during any inflammatory condition causing tissue damage could contribute to the pathogenic fibrotic events accompanying the healing response; for instance, the inflammation resulting from tissue engraftment could cause the formation of fibrotic scars in the grafted tissue, even in cases where the immune system deals with hard to clear infections, fibrotic scars could follow and cause severe adverse effects. A good example of such a complication is post-Covid19 lung fibrosis which could impair the life of the affected individuals with extensive lung involvement. However, effective therapies that halt or slow down the progression of fibrosis are missing in the current clinical settings. Considering the immunomodulatory and regenerative potential of distinct stem cell types, their application as an anti-fibrotic agent, capable of attenuating tissue fibrosis has been investigated by many researchers. Although the majority of the studies addressing the anti-fibrotic effects of stem cells indicated their potent capabilities, the underlying mechanisms, and pathways by which these cells could impact fibrotic processes remain poorly understood. Here, we first, review the properties of various stem cell types utilized so far as anti-fibrotic treatments and discuss the challenges and limitations associated with their applications in clinical settings; then, we will summarize the general and organ-specific mechanisms and pathways contributing to tissue fibrosis; finally, we will describe the mechanisms and pathways considered to be employed by distinct stem cell types for exerting anti-fibrotic events.

Therapeutic role of exosomes and conditioned medium in keloid and hypertrophic scar and possible mechanisms

Exosomes, ranging from 40 to 160 nm in diameter, are extracellular lipid bilayer microvesicles that regulate the body's physiological and pathological processes and are secreted by cells that contain proteins, nucleic acids, amino acids and other metabolites. Previous studies suggested that mesenchymal stem cell (MSC)-derived exosomes could either suppress or support keloid and hypertrophic scar progression. Although previous research has identified the potential value of MSC-exosomes in keloid and hypertrophic scar, a comprehensive analysis of different sources of MSC-exosome in keloid and hypertrophic scar is still lacking. This review mainly discusses different insights regarding the roles of MSC-exosomes in keloid and hypertrophic scar treatment and summarizes possible underlying mechanisms.

An updated review of the immunological mechanisms of keloid scars

Keloid is a type of disfiguring pathological scarring unique to human skin. The disorder is characterized by excessive collagen deposition. Immune cell infiltration is a hallmark of both normal and pathological tissue repair. However, the immunopathological mechanisms of keloid remain unclear. Recent studies have uncovered the pivotal role of both innate and adaptive immunity in modulating the aberrant behavior of keloid fibroblasts. Several novel therapeutics attempting to restore regulation of the immune microenvironment have shown variable efficacy. We review the current understanding of keloid immunopathogenesis and highlight the potential roles of immune pathway-specific therapeutics.

Advances in the pathogenesis and clinical application prospects of tumor biomolecules in keloid

Keloid scarring is a kind of pathological healing manifestation after skin injury and possesses various tumor properties, such as the Warburg effect, epithelial-mesenchymal transition (EMT), expression imbalances of apoptosis-related genes and the presence of stem cells. Abnormal expression of tumor signatures is critical to the initiation and operation of these effects. Although previous experimental studies have recognized the potential value of a single or several tumor biomolecules in keloids, a comprehensive evaluation system for multiple tumor signatures in keloid scarring is still lacking. This paper aims to summarize tumor biomolecules in keloids from the perspectives of liquid biopsy, genetics, proteomics and epigenetics and to investigate their mechanisms of action and feasibility from bench to bedside. Liquid biopsy is suitable for the early screening of people with keloids due to its noninvasive and accurate performance. Epigenetic biomarkers do not require changes in the gene sequence and their reversibility and tissue specificity make them ideal therapeutic targets. Nonetheless, given the ethnic specificity and genetic predisposition of keloids, more large-sample multicenter studies are indispensable for determining the prevalence of these signatures and for establishing diagnostic criteria and therapeutic efficacy estimations based on these molecules.

Research update of adipose tissue-based therapies in regenerative dermatology

Mesenchymal stromal/stem cells (MSCs) have a spontaneous propensity to support tissue homeostasis and regeneration. Among the several sources of MSCs, adipose-derived tissue stem cells (ADSCs) have received major interest due to the higher mesenchymal stem cells concentration, ease, and safety of access. However, since a significant part of the natural capacity of ADSCs to repair damaged tissue is ascribable to their secretory activity that combines mitogenic factors, cytokines, chemokines, lipids, and extracellular matrix components, several studies focused on cell-free strategies. Furthermore, adipose cell-free derivatives are becoming more attractive especially for non-volumizing purposes, such as most dermatological conditions. However, when keratinocytes, fibroblasts, melanocytes, adipocytes, and hair follicle cells might not be locally sourced, graft of materials containing concentrated ADSCs is preferred. The usage of extracellular elements of adipose tissue aims to promote a self-autonomous regenerative microenvironment in the receiving area restoring physiological homeostasis. Hence, ADSCs or their paracrine activity are currently being studied in several dermatological settings including wound healing, skin fibrosis, burn, and aging.The present work analyzing both preclinical and clinical experiences gives an overview of the efficacy of adipose tissue-derivatives like autologous fat, the stromal vascular fraction (SVF), purified ADSCs, secretome and extracellular matrix graft in the field of regenerative medicine for the skin.

TGF-β1 and CD68 immunoexpression in capsules formed by textured implants with and without mesh coverage: a study on female rats

PURPOSE

To evaluate fibrosis formation and number of macrophages in capsules formed around textured implants without and with mesh coverage.

METHODS

Fibrosis was analyzed through transforming growth factor-beta 1 (TGF-β1) immunomarker expression and the number of macrophages through CD68 percentage of cells in magnified field. Sixty female Wistar rats were distributed into two groups of 30 rats (unmeshed and meshed). Each group was then subdivided into two subgroups for postoperative evaluation after 30 and 90 days. The p value was adjusted by Bonferroni lower than 0.012.

RESULTS

No difference was observed in fibrosis between meshed and unmeshed groups (30 days p = 0.436; 90 days p = 0.079) and from 30 to 90 days in the unmeshed group (p = 0.426). The meshed group showed higher fibrosis on the 90th day (p = 0.001). The number of macrophages was similar between groups without and with mesh coverage (30 days p = 0.218; 90 days p = 0.044), and similar between subgroups 30 and 90 days (unmeshed p = 0.085; meshed p = 0.059).

CONCLUSIONS

In the meshed group, fibrosis formation was higher at 90 days and the mesh-covered implants produced capsules similar to microtextured ones when analyzing macrophages. Due to these characteristics, mesh coating did not seem to significantly affect the local fibrosis formation.

Comparison of the Effects of Acellular Dermal Matrix and Montelukast on Radiation-Induced Peri-implant Capsular Formation in Rabbits

PURPOSE

Capsular contracture (CC) is a troublesome complication after breast surgery with breast implants, and the risk increases in breast cancer patients after radiotherapy. Studies investigating leukotriene antagonists (eg, montelukast, zafirlukast) found that the acellular dermal matrix (ADM) can help prevent CC. We aimed to compare the effects of ADM and montelukast on CC after irradiation.

METHODS

Eighteen New Zealand white rabbits were randomly divided into 3 groups of 6 each. Miniature cohesive gel implants were inserted into the pocket under the latissimus dorsi muscle. The lateral part was uncovered by the latissimus dorsi muscle. Six animals were included in the control group. In experimental group A (EG-A) (n = 6), the site was partially wrapped with ADM but not covered with muscle. Montelukast (Singulair, 0.2 mg/kg) was administered in experimental group B (EG-B) (n = 6) daily. Groups were irradiated at postoperative day 21 with Co-60 γ rays (25 Gy, single fraction) at the peri-implant area. Rabbits were sacrificed 12 weeks after surgery; implants with peri-implant capsule were harvested. Capsule thickness, collagen pattern, myofibroblast, and transforming growth factor (TGF) β1/2 levels in the peri-implant capsule were evaluated.

RESULTS

On histological evaluation, the capsule was thinner on the lateral aspect (covered with ADM) in EG-A (P = 0.004) and the entire capsule in EG-B (P = 0.004) than in the control group. However, there was no significant difference between EG-A and EG-B (P = 0.073). The collagen distribution pattern was more parallel with low density in the lateral capsular aspect in EG-A, but in the entire capsule in EG-B. The myofibroblast amount (EG-A, P = 0.031; EG-B, P = 0.016) and levels of TGF-β1 and TGF-β2 were reduced in the experimental groups (TGF-β1, EG-A, P = 0.019; TGF-β1, EG-B, P = 0.045; TGF-β2, EG-A, P = 0.018; TGF-β2, EG-B, P = 0.022). There was no significant difference between EG-A and EG-B (myofibroblast, P = 0.201; TGF-β1, P = 0.665; TGF-β2, P = 0.665).

CONCLUSIONS

Acellular dermal matrix and montelukast have a prophylactic effect for CC even when the breast is irradiated. There was no significant difference between ADM and montelukast in preventing capsular formation. The difference is that ADM will only have the effect of covering the capsular formation with ADM and montelukast can cause systemic effects or complications.

Therapeutic Strategies by Regulating Interleukin Family to Suppress Inflammation in Hypertrophic Scar and Keloid

Hypertrophic scar (HS) and keloid are fibroproliferative disorders (FPDs) of the skin due to aberrant wound healing, which cause disfigured appearance, discomfort, dysfunction, psychological stress, and patient frustration. The unclear pathogenesis behind HS and keloid is partially responsible for the clinical treatment stagnancy. However, there are now increasing evidences suggesting that inflammation is the initiator of HS and keloid formation. Interleukins are known to participate in inflammatory and immune responses, and play a critical role in wound healing and scar formation. In this review, we summarize the function of related interleukins, and focus on their potentials as the therapeutic target for the treatment of HS and keloid.

Extracellular Vesicles from Thapsigargin-Treated Mesenchymal Stem Cells Ameliorated Experimental Colitis via Enhanced Immunomodulatory Properties

Therapeutic applications of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) have attracted considerable attention because of their immunomodulatory properties against immune-mediated, inflammatory diseases. Here, we demonstrated enhanced immunomodulatory properties of EVs secreted from endoplasmic reticulum (ER) stress inducer thapsigargin (TSG)-primed human Wharton's jelly-derived MSCs (WJ-MSCs). EVs from TSG-primed WJ-MSCs (TSG-EV) showed increased yield and expression of immunomodulatory factors, such as transforming growth factor-β1 (TGFβ), cyclooxygenase-2 (COX2), and especially indoleamine 2,3-dioxygenase (IDO), compared to control EVs. TSG-EV showed a significantly enhanced immunosuppressive effect on human peripheral blood-derived T cell proliferation and Th1 and Th17 differentiation, whereas Treg and M2-type macrophage were enriched compared to a control EV-treated group. Furthermore, TSG-EV substantially mitigated mouse experimental colitis by reducing the inflammatory response and maintaining intestinal barrier integrity. A significant increase of Tregs and M2-type macrophages in colitic colons of a TSG-EV-treated mouse suggests an anti-inflammatory effect of TSG-EV in colitis model, possibly mediated by Treg and macrophage polarization. These data indicate that TSG treatment promoted immunomodulatory properties of EVs from WJ-MSCs, and TSG-EV may provide a new therapeutic approach for treatment of colitis.

Anti-fibrotic effects of different sources of MSC in bleomycin-induced lung fibrosis in C57BL6 male mice

BACKGROUND AND OBJECTIVE

IPF is a fatal and debilitating lung disorder increasing in incidence worldwide. To date, two approved treatments only slow disease progression, have multiple side effects and do not provide a cure. MSC have promising therapeutic potential as a cell-based therapy for many lung disorders based on the anti-fibrotic properties of the MSC.

METHODS

Critical questions remain surrounding the optimal source, timing and efficacy of cell-based therapies. The present study examines the most effective sources of MSC. Human MSC were derived from adipose, WJ, chorionic membrane (CSC) and chorionic villi (CVC). MSC were injected into the ageing mouse model of BLM-induced lung fibrosis.

RESULTS

All sources decreased Aschroft and hydroxyproline levels when injected into BLM-treated mice at day 10 with the exception of CSC cells that did not change hydroxyproline levels. There were also decreases in mRNA expression of αv -integrin and TNFα in all sources except CSC. Only ASC- and WJ-derived cells reduced AKT and MMP-2 activation, while Cav-1 was increased by ASC treatment as previously reported. BLM-induced miR dysregulation of miR-29 and miR-199 was restored only by ASC treatment.

CONCLUSION

Our data suggest that sources of MSC may differ in the pathway(s) involved in repair.

Skin regeneration is accelerated by a lower dose of multipotent mesenchymal stromal/stem cells-a paradigm change

Background

Multipotent mesenchymal stromal/stem cell (MSC) therapy is under investigation in promising (pre-)clinical trials for wound healing, which is crucial for survival; however, the optimal cell dosage remains unknown. The aim was to investigate the efficacy of different low-to-high MSC dosages incorporated in a biodegradable collagen-based dermal regeneration template (DRT) Integra®.

Methods

We conducted a porcine study (N = 8 Yorkshire pigs) and seeded between 200 and 2,000,000 cells/cm² of umbilical cord mesenchymal stromal/stem cells on the DRT and grafted it onto full-thickness burn excised wounds. On day 28, comparisons were made between the different low-to-high cell dose groups, the acellular control, a burn wound, and healthy skin.

Result

We found that the low dose range between 200 and 40,000 cells/cm² regenerates the full-thickness burn excised wounds most efficaciously, followed by the middle dose range of 200,000–400,000 cells/cm² and a high dose of 2,000,000 cells/cm². The low dose of 40,000 cells/cm² accelerated reepithelialization, reduced scarring, regenerated epidermal thickness superiorly, enhanced neovascularization, reduced fibrosis, and reduced type 1 and type 2 macrophages compared to other cell dosages and the acellular control.

Conclusion

This regenerative cell therapy study using MSCs shows efficacy toward a low dose, which changes the paradigm that more cells lead to better wound healing outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02131-6.

An Update on the Potential of Mesenchymal Stem Cell Therapy for Cutaneous Diseases

Mesenchymal stem or stromal cells (MSCs) are nonhematopoietic postnatal stem cells with self-renewal, multipotent differentiation, and potent immunomodulatory and anti-inflammatory capabilities, thus playing an important role in tissue repair and regeneration. Numerous clinical and preclinical studies have demonstrated the potential application of MSCs in the treatment of tissue inflammation and immune diseases, including inflammatory skin diseases. Therefore, understanding the biological and immunological characteristics of MSCs is important to standardize and optimize MSC-based regenerative therapy. In this review, we highlight the mechanisms underlying MSC-mediated immunomodulation and tissue repair/regeneration and present the latest development of MSC-based clinical trials on cutaneous diseases.

Inhibition of growth of Asian keloid cells with human umbilical cord Wharton's jelly stem cell-conditioned medium

Background

Keloid formation occurs in Caucasian, African, and Asian populations and is a severe psychosocial burden on patients. There is no permanent treatment for this problem as its pathogenesis is not properly understood. Furthermore, differences in keloid behavior between ethnic groups are not known. It has been hypothesized that keloids behave like benign tumors because of their uncontrolled growth. The present study evaluated the tumoricidal properties of human Wharton’s jelly stem cell-conditioned medium (hWJSC-CM) on fresh Asian keloid cells (AKCs).

Methods

Human Wharton’s jelly stem cells (hWJSCs) and AKCs were isolated based on our previous methods. hWJSCs and human skin fibroblasts (HSF) (controls) were used to collect hWJSC-CM and HSF-conditioned medium (HSF-CM). AKCs were treated with hWJSC-CM and HSF-CM in vitro and in vivo in a human keloid xenograft SCID mouse model. The inhibitory effect of hWJSC-CM on AKCs was tested in vitro using various assays and in vivo for attenuation/abrogation of AKC tumors created in a xenograft mouse model.

Results

qRT-PCR analysis showed that the genes FN1, MMP1, and VCAN were significantly upregulated in AKCs and ANXA1, ASPN, IGFBP7, LGALS1, and PTN downregulated. AKCs exposed to hWJSC-CM in vitro showed significant decreases in cell viability and proliferation, increases in Annexin V-FITC+ cell numbers, interruptions of the cell cycle at Sub-G1 and G2/M phases, altered CD marker expression, downregulated anti-apoptotic-related genes, and upregulated pro-apoptotic and autophagy-related genes compared to controls. When AKCs were administered together with hWJSC-CM into immunodeficient mice there were no keloid tumors formed in 7 mice (n = 10) compared to the untreated control mice. When hWJSC-CM was injected directly into keloid tumors created in mice there were significant reductions in keloid tumor volumes and weights in 30 days.

Conclusions

hWJSC-CM inhibited the growth of AKCs in vitro and in xenograft mice, and it may be a potential novel treatment for keloids in the human. The specific molecule(s) in hWJSC-CM that induce the anti-keloid effect need to be identified, characterized, and tested separately in larger preclinical and clinical studies.

Effect of Intracorporeal Human Adipose-Derived Stem Cells (hADSCs) on Corpora Cavernosa Transforming Growth Factor β1 (TGFβ1) and Collagen Type I Concentration in Wistar Rat Priapism Model

Introduction

The ischemic process in priapism can lead to displacement of normal tissue with fibrotic tissue, due to collagen deposition, and eventually leads to erectile dysfunction. Many studies have identified that the supernatant of adipose tissue–derived stem cells (ADSCs) significantly ameliorates fibrosis of different tissue, but limited attention has been paid to its efficacy on fibrosis of the corpora cavernosa.

Methods

A total of 22 Wistar rats divided into five groups, with two groups each consisting of five male wistar rats with priapism without human ADSC (hADSC) therapy (group I) and two other groups consisting of five rats with priapism, were given 10⁶ cells' intracorporeal hADSC injection after 12 hours of penile clamping (group II) were euthanized after 2 and 4 weeks of observation. The last group consisted of two rats without any treatment or model (group III). Following euthanasia, penises were harvested for TGFβ₁ and collagen type I measurement using ELISA. Statistical analysis using independent-sample t-tests was done with SPSS 21.0.

Results

Penile TGFβ₁ concentration in the treatment group was significantly lower in the second and fourth weeks of observation (p₂=0.004, p₄=0.003), and collagen type I was significantly lower in the second and fourth weeks (p₂=0.003, p₄=0.011).

Conclusion

Intracorporeal hADSC injection limited the fibrosis process in a priapism model. Although the mechanism was unclear, it may be related to the potential of hADSCs to produce various growth factors that could limit TGFβ₁ and collagen production.

Handheld instrument for wound-conformal delivery of skin precursor sheets improves healing in full-thickness burns

The current standard of care for patients with severe large-area burns consists of autologous skin grafting or acellular dermal substitutes. While emerging options to accelerate wound healing involve treatment with allogeneic or autologous cells, delivering cells to clinically relevant wound topologies, orientations, and sizes remains a challenge. Here, we report the one-step in situ formation of cell-containing biomaterial sheets using a handheld instrument that accommodates the topography of the wound. In an approach that maintained cell viability and proliferation, we demonstrated conformal delivery to surfaces that were inclined up to 45° with respect to the horizontal. In porcine pre-clinical models of full-thickness burn, we delivered mesenchymal stem/stromal cell-containing fibrin sheets directly to the wound bed, improving re-epithelialization, dermal cell repopulation, and neovascularization, indicating that this device could be introduced in a clinical setting improving dermal and epidermal regeneration.

Keloids: Current and emerging therapies

Keloids are pathological scars that grow over time and extend beyond the initial site of injury after impaired wound healing. These scars frequently recur and rarely regress. They are aesthetically disfiguring, can cause pain, itching, discomfort as well as psychological stress, often affecting quality of life. Many treatment modalities, including surgical and non-surgical, have been explored and have been reported to be beneficial; however, none have been absolutely satisfactory or optimal for the treatment of all keloid subtypes to date. This poses a major challenge to clinicians. Often, a combinational therapeutic approach appears to offer the best results with higher patient satisfaction compared to monotherapy. The aetiopathogenesis of keloids is not fully elucidated; however, with recent advances in molecular biology and genetics, insight is being gained on the complex process of scar formation and hence new therapeutic and management options for keloids. In this paper, we explore the literature and summarise the general concepts surrounding keloid development and review both current (corticosteroids, surgical excision, silicone-based products, pressure therapy, radiotherapy, cryotherapy, laser therapy, imiquimod and 5-fluorouracil) and emerging (stem cell therapy, mitomycin C, verapamil, interferons, bleomycin, botulinum toxin type A and angiotensin-converting enzyme inhibitors) treatments. Increased knowledge and understanding in this area may potentially lead to the discovery and development of novel therapeutic options that are more efficacious for all keloid types.

LAY SUMMARY

Keloids are problematic scars that are difficult to treat and manage. The aetiopathogenesis of keloids is not clear; however, recent advances in molecular biology and genetics are beginning to shed light on the underlying mechanisms implicated in keloid scar formation which will hopefully lead to the development of treatment options for all keloid types. This review summarises current and emerging therapies.

In Vitro and Ex Vivo Models for Functional Testing of Therapeutic Anti-scarring Drug Targets in Keloids

Significance: Keloids are benign fibro-proliferative raised dermal lesions that spread beyond the original borders of the wound, continue to grow, rarely regress, and are the most common in pigmented individuals after an abnormal wound healing response. The current treatment failure and respective challenges involved highlighting the underlying issue that the etiopathogenesis of keloids is still not well understood. Disease models are required to better understand the disease pathogenesis. It is not possible to establish keloids in animals because of the uniqueness of this disease to human skin. To address this challenge, along these lines, non-animal reproducible models are vital in investigating molecular mechanisms of keloid pathogenesis and therapeutics development. Recent Advances: Various non-animal models have been developed to better understand the molecular mechanisms involved in keloid scarring and aid in identifying and evaluating the therapeutic potential of novel drug candidates. In this scenario, the current review aims at describing in vitro monocultures, co-cultures, organotypic cultures, and ex vivo whole skin keloid tissue organ culture models. Critical Issues and Future Directions: Current treatment options for keloids are far from securing a cure or preventing disease recurrence. Identifying universally accepted effective therapy for keloids has been hampered by the absence of appropriate disease model systems. Animal models do not accurately mimic the disease, thus non-animal model systems are pivotal in keloid research. The use of these models is essential not only for a better understanding of disease biology but also for identifying and evaluating novel drug targets.

Enhanced Therapeutic Potential of the Secretome Released from Adipose-Derived Stem Cells by PGC-1α-Driven Upregulation of Mitochondrial Proliferation

Peroxisome proliferator activated receptor λ coactivator 1α (PGC-1α) is a potent regulator of mitochondrial biogenesis and energy metabolism. In this study, we investigated the therapeutic potential of the secretome released from the adipose-derived stem cells (ASCs) transfected with PGC-1α (PGC-secretome). We first generated PGC-1α-overexpressing ASCs by transfecting ASCs with the plasmids harboring the gene encoding PGC-1α. Secretory materials released from PGC-1α-overexpressing ASCs were collected and their therapeutic potential was determined using in vitro (thioacetamide (TAA)-treated AML12 cells) and in vivo (70% partial hepatectomized mice) models of liver injury. In the TAA-treated AML12 cells, the PGC-secretome significantly increased cell viability, promoted expression of proliferation-related markers, such as PCNA and p-STAT, and significantly reduced the levels of reactive oxygen species (ROS). In the mice, PGC-secretome injections significantly increased liver tissue expression of proliferation-related markers more than normal secretome injections did (p < 0.05). We demonstrated that the PGC-secretome does not only have higher antioxidant and anti-inflammatory properties, but also has the potential of significantly enhancing liver regeneration in both in vivo and in vitro models of liver injury. Thus, reinforcing the mitochondrial antioxidant potential by transfecting ASCs with PGC-1α could be one of the effective strategies to enhance the therapeutic potential of ASCs.

Promotion of dermal regeneration using pullulan/gelatin porous skin substitute

Tissue-engineered dermal substitutes represent a promising approach to improve wound healing and provide more sufficient regeneration, compared with current clinical standards on care of large wounds, early excision, and grafting of autografts. However, inadequate regenerative capacity, impaired regeneration/degradation profile, and high cost of current commercial tissue-engineered dermal regeneration templates hinder their utilization, and the development of an efficient and cost-effective tissue-engineered dermal substitute remains a challenge. Inspired from our previously reported data on a pullulan/gelatin scaffold, here we present a new generation of a porous pullulan/gelatin scaffold (PG2) served as a dermal substitute with enhanced chemical and structural characteristics. PG2 shows excellent biocompatibility (viability, migration, and proliferation), assessed by in vitro incorporation of human dermal fibroblasts in comparison with the Integra® dermal regeneration template (Control). When applied on a mouse full-thickness excisional wound, PG2 shows rapid scaffold degradation, more granulation tissue, more collagen deposition, and more cellularity in comparison with Control at 20 days post surgery. The faster degradation is likely due to the enhanced recruitment of inflammatory macrophages to the scaffold from the wound bed, and that leads to earlier maturation of granulation tissue with less myofibroblastic cells. Collectively, our data reveal PG2's characteristics as an applicable dermal substitute with excellent dermal regeneration, which may attenuate scar formation.

Role of mechanical and thermal damage in pericapsular inflammatory response to injectable silicone in a rabbit model

Silicone is used widely for tissue augmentation in humans. However, late complications, such as delayed inflammation and capsular contracture, remain uncharacterized, despite their importance. In the present study, we aimed to determine whether mechanical and thermal damage induce capsular inflammation around a foreign body, and elucidate the biological mechanism underlying this phenomenon. We injected silicone into the subcutaneous layer of the skin of New Zealand white rabbits. The rabbits were divided into two groups: the control group received no treatment; in the experimental group, external force was applied near the injection silicone using high-intensity focused ultrasound (HIFU). Tissues near the injected silicone were harvested from both groups on Days 4, 7, and 30 after HIFU treatment for comparative analysis. Visual and histological examinations showed clearly increased inflammation in the experimental group compared with that in the control group. Furthermore, capsular tissue from the experimental group displayed markedly increased collagen production. Immunofluorescence revealed marked activation of macrophages in the early stages of inflammation (Days 4 and 7 after HIFU treatment), which decreased on Day 30. Assessment of cytokine activation showed significantly increased expression of heat shock protein (HSP)27, HSP60, HSP70, toll-like receptor (TLR)2, TLR4, and interleukin-8 in the experimental group. The expression of transforming growth factor-β1 did not increase significantly in the experimental group. In conclusion, damage to tissues around the injected silicone induced capsular inflammation. Macrophages and damage-associated molecular pattern molecules were involved in the early stages of inflammation. HSP release activated TLRs, which subsequently activated innate immunity and induced the inflammatory response.

Multi-dimensional models for functional testing of keloid scars: In silico, in vitro, organoid, organotypic, ex vivo organ culture, and in vivo models

Keloid scars are described as benign fibro-proliferative dermal outgrowths that commonly occur in pigmented skin post cutaneous injury, and continue to grow beyond the boundary of the original wound margin. There is a lack of thorough understanding of keloid pathogenesis and thus keloid therapeutic options remain ill-defined. In view of the poor response to current therapy and high recurrence rates, there is an unmet need in improving our knowledge and therefore in identifying targeted and effective treatment strategies in management of keloids. Keloid research however, is hampered by a lack of relevant animal models as keloids do not spontaneously occur in animals and are unique to human skin. Therefore, developing novel animal models and nonanimal models for functional evaluation of keloid cells and tissue for better understanding their pathobiology and response to putative candidate therapies are essential. Here, we present the key concepts and relevant emerging research on two-dimensional and three-dimensional cell and tissue models for functional testing of keloid scars. We will describe in detail current models including in vitro mono- and co-cultures, multi-cellular spheroids (organoids) and organotyopic cultures, ex vivo whole skin keloid tissue organ culture models as well as in vivo human patient models. Finally, we discuss the role played by time as the fourth dimension in a novel model that involves sequential temporal biopsies of human patients with keloids (a so called 4D in vivo human model). The use of these unique models will no doubt prove pivotal in identification of new drug targets as well as biomarkers, in functional testing of emerging novel therapeutics, and in enhancing our understanding of keloid disease biology.

Hyperbaric oxygen therapy improves the effect of keloid surgery and radiotherapy by reducing the recurrence rate

OBJECTIVE

Keloids are exuberant cutaneous scars that form due to abnormal growth of fibrous tissue following an injury. The primary aim of this study was to assess the efficacy and mechanism of hyperbaric oxygen therapy (HBOT) to reduce the keloid recurrence rate after surgical excision and radiotherapy.

METHODS

(1) A total of 240 patients were randomly divided into two groups. Patients in the HBOT group (O group) received HBOT after surgical excision and radiotherapy. Patients in the other group were treated with only surgical excision and radiotherapy (K group). (2) Scar tissue from recurrent patients was collected after a second operation. Hematoxylin and eosin (H&E) staining was used to observe keloid morphology. Certain inflammatory factors (interleukin-6 (IL-6), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α), nuclear factor κB (NF-κB), and vascular endothelial growth factor (VEGF)) were measured using immunohistochemical staining.

RESULTS

(1) The recurrence rate of the O group (5.97%) was significantly lower than that of the K group (14.15%), P<0.05. Moreover, patients in the O group reported greater satisfaction than those in the K group (P<0.05). (2) Compared with the recurrent scar tissue of the K group, the expression levels of the inflammatory factors were lower in the recurrent scar tissue of the O group.

CONCLUSIONS

Adjunctive HBOT effectively reduces the keloid recurrence rate after surgical excision and radiotherapy by improving the oxygen level of the tissue and alleviating the inflammatory process.

A silk fibroin/decellularized extract of Wharton's jelly hydrogel intended for cartilage tissue engineering

A hybrid hydrogel was obtained from decellularized extract from Wharton's jelly (DEWJ) and silk fibroin (SF) and characterized for cartilage tissue engineering. Wharton's jelly was used due to its similarity with articular cartilage in extracellular matrix composition. Also, silk fibroin has good mechanical properties which make this construct appropriate for cartilage repair. Decellularization of Wharton's jelly was verified by DAPI staining, DNA quantification, and PCR analysis. Then, the biochemical composition of DEWJ was determined by ELISA kits for total proteins, collagens, sulfated glycosaminoglycans (sGAG), and transforming growth factor β1 (TGF-β1). After fabricating pure SF and SF/DEWJ hybrid hydrogels, their physical and mechanical properties were characterized by FESEM, Fourier-transform infrared spectroscopy (FTIR) and rheological assays (amplitude and frequency sweeps). Furthermore, cell viability and proliferation were assessed by MTT assay. The results have shown that DEWJ in hybrid hydrogels enhances mechanical properties of the construct relative to pure SF hydrogels. Also, this extract at its 40% concentration in culture media and 20% or 40% concentrations in SF/DEWJ hybrid hydrogels significantly increases population of the cells compared to control and pure SF hydrogel after 7 days. In conclusion, this study proposes the potential of SF/DEWJ hybrid hydrogels for cartilage tissue engineering applications.

5-HT1A Receptor Function Makes Wound Healing a Happier Process

Skin wound healing is a multistage phenomenon that is regulated by cell–cell interplay and various factors. Endogenous serotonin is an important neurotransmitter and cytokine. Its interaction with the serotonin 1A receptor (5-HTR1A) delivers downstream cellular effects. The role of serotonin (5-hydroxytryptamine, 5-HT) and the 5-HT1A receptor has been established in the regeneration of tissues such as the liver and spinal motor neurons, prompting the investigation of the role of 5-HT1A receptor in skin healing. This study assessed the role of 5-HT1A receptor in excisional wound healing by employing an excisional punch biopsy model on 5-Ht1a receptor knockout mice. Post-harvest analysis revealed 5-Ht1a receptor knockout mice showed impaired skin healing, accompanied by a greater number of F4/80 macrophages, which prolongs the inflammatory phase of wound healing. To further unravel this phenomenon, we employed the 5-HT1A receptor agonist [(R)-(+)-8-Hydroxy-DPAT hydrobromide] as a topical cream treatment in an excisional punch biopsy model. The 5-HT1A receptor agonist treated group showed a smaller wound area, scar size, and improved neovascularization, which contributed to improve healing outcomes as compared to the control. Collectively, these findings revealed that serotonin and 5-HT1A receptor play an important role during the healing process. These findings may open new lines of investigation for the potential treatment alternatives to improve skin healing with minimal scarring.

Exosomes from acellular Wharton's jelly of the human umbilical cord promotes skin wound healing

BACKGROUND

Compromised wound healing has become a global public health challenge which presents a significant psychological, financial, and emotional burden on patients and physicians. We recently reported that acellular gelatinous Wharton's jelly of the human umbilical cord enhances skin wound healing in vitro and in vivo in a murine model; however, the key player in the jelly which enhances wound healing is still unknown.

METHODS

We performed mass spectrometry on acellular gelatinous Wharton's jelly to elucidate the chemical structures of the molecules. Using an ultracentrifugation protocol, we isolated exosomes and treated fibroblasts with these exosomes to assess their proliferation and migration. Mice were subjected to a full-thickness skin biopsy experiment and treated with either control vehicle or vehicle containing exosomes. Isolated exosomes were subjected to further mass spectrometry analysis to determine their cargo.

RESULTS

Subjecting the acellular gelatinous Wharton's jelly to proteomics approaches, we detected a large amount of proteins that are characteristic of exosomes. Here, we show that the exosomes isolated from the acellular gelatinous Wharton's jelly enhance cell viability and cell migration in vitro and enhance skin wound healing in the punch biopsy wound model in mice. Mass spectrometry analysis revealed that exosomes of Wharton's jelly umbilical cord contain a large amount of alpha-2-macroglobulin, a protein which mimics the effect of acellular gelatinous Wharton's jelly exosomes on wound healing.

CONCLUSIONS

Exosomes are being enriched in the native niche of the umbilical cord and can enhance wound healing in vivo through their cargo. Exosomes from the acellular gelatinous Wharton's jelly and the cargo protein alpha-2-macroglobulin have tremendous potential as a noncellular, off-the-shelf therapeutic modality for wound healing.

Efficacy of lentivirus‑mediated Drosophila melanogaster deoxyribonucleoside kinase combined with (E)‑5‑(2‑bromovinyl)‑2'‑deoxyuridine or 1‑β‑D‑arabinofuranosylthymine therapy in human keloid fibroblasts

Keloid scarring is a type of fibroproliferative disease with a high recurrence rate. However, no effective treatment is currently available. Combined therapy with recombinant lentivirus‑mediated Drosophila melanogaster deoxyribonucleoside kinase (Dm‑dNK) and prodrug has been widely studied and used for cancer treatment. Due to the similarities between keloid scars and tumors, the aim of the present study was to investigate the efficacy of a Dm‑dNK/nucleoside analog system for the treatment of keloid scars. Recombinant lentivirus expression of the Dm‑dNK suicide gene was assessed. Western blotting was used to examine the protein expression of lentivirus mediated Dm‑dNK in keloid fibroblasts. Enzyme activity assays were conducted using [3H]‑labeled substrates. Furthermore, cytotoxicity and bystander effects were evaluated using MTT assays. The expression of green fluorescent protein was observed using fluorescence microscope and results indicated that there was no notable difference in lentivirus infectivity between the multiplicity of infection (MOI) of 1 and 10 in cells. Notably, western blotting revealed that Dm‑dNK was stably expressed in keloid fibroblasts and the enzymatic activity assays revealed that the enzyme was activated following introduction into the keloid fibroblasts via the lentivirus. The cytotoxicity and bystander effects of Dm‑dNK combined with cytotoxic nucleoside analogs were both observed in Dm‑dNK+ keloid fibroblasts. These results demonstrated that the lentivirus‑mediated Dm‑dNK therapy may be effective in treating keloid fibroblasts, which provides some evidence for the use of Dm‑dNK/prodrug therapy for keloid treatment in vivo in the future.

The Role of Serotonin during Skin Healing in Post-Thermal Injury

Post-burn trauma significantly raises tissue serotonin concentration at the initial stages of injury, which leads us to investigate its possible role in post burn wound healing. Therefore, we planned this study to examine the role of serotonin in wound healing through in vitro and in vivo models of burn injuries. Results from in vitro analysis revealed that serotonin decreased apoptosis and increased cell survival significantly in human fibroblasts and neonatal keratinocytes. Cellular proliferation also increased significantly in both cell types. Moreover, serotonin stimulation significantly accelerated the cell migration, resulting in narrowing of the scratch zone in human neonatal keratinocytes and fibroblasts cultures. Whereas, fluoxetine (a selective serotonin reuptake inhibitor) and ketanserin (serotonin receptor 2A inhibitor) reversed these effects. Scald burn mice model (20% total body surface area) showed that endogenous serotonin improved wound healing process in control group, whereas fluoxetine and ketanserin treatments (disruptors of endogenous serotonin stimulation), resulted in poor reepithelization, bigger wound size and high alpha smooth muscle actin (α-SMA) count. All of these signs refer a prolonged differentiation state, which ultimately exhibits poor wound healing outcomes. Collectively, data showed that the endogenous serotonin pathway contributes to regulating the skin wound healing process. Hence, the results of this study signify the importance of serotonin as a potential therapeutic candidate for enhancing skin healing in burn patients.

Scar management in burn injuries using drug delivery and molecular signaling: Current treatments and future directions

In recent decades, there have been tremendous improvements in burn care that have allowed patients to survive severe burn injuries that were once fatal. However, a major limitation of burn care currently is the development of hypertrophic scars in approximately 70% of patients. This significantly decreases the quality of life for patients due to the physical and psychosocial symptoms associated with scarring. Current approaches to manage scarring include surgical techniques and non-surgical methods such as laser therapy, steroid injections, and compression therapy. These treatments are limited in their effectiveness and regularly fail to manage symptoms. As a result, the development of novel treatments that aim to improve outcomes and quality of life is imperative. Drug delivery that targets the molecular cascades of wound healing to attenuate or prevent hypertrophic scarring is a promising approach that has therapeutic potential. In this review, we discuss current treatments for scar management after burn injury, and how drug delivery targeting molecular signaling can lead to new therapeutic strategies.

The impact of high hydrostatic pressure (40 MPa and 60 MPa) on the apoptosis rates and functional activity of cryopreserved porcine mesenchymal stem cells

The aim of the present study was to examine the influence of two varied high hydrostatic pressure (HHP) values on the apoptosis (assessing caspase-8, survivin, CAD, Bax, BclxL and BclxS) and functional activity (using cocultures with bovine embryos) of porcine mesenchymal stem cells (pBMSCs). pBMSCs were isolated from porcine bone marrow and cultured in vitro. Before cryopreservation and storage in liquid nitrogen, pBMSCs were subjected to HHP values of 40 MPa and 60 MPa for 1 h at 24°C. After thawing, the cells were analysed for caspase-8 activity and protein expression of survivin, CAD, Bax, BclxL and BclxS. To indirectly test the influence of HHP on the functional activity of pBMSCs, in vitro maturated bovine oocytes were fertilized in vitro, and the obtained embryos were cultured under 4 different conditions: 1. monoculture in SOF medium; 2. coculture with pBMSCs in SOF medium; 3. coculture with pBMSCs subjected to 40 MPa HHP in SOF medium and 4. coculture with pBMSCs subjected to 60 MPa HHP in SOF medium. The quality of the developed blastocysts was analysed by TUNEL assay. HHP did not induce apoptosis in pBMSCs, as no significant difference was noted in the expression of any of the analysed apoptosis- related proteins between pBMSCs subjected to HHP (40 MPa or 60 MPa) and control. The highest number of obtained blastocysts was observed when the embryos were cultured in SOF. A highly significant difference (P<0.005) was noted between embryos cultured in SOF and embryos cultured in the presence of pBMSCs subjected to 60 MPa HHP or untreated pBMSCs. A significant difference (P<0.05) was noted between embryos cultured in SOF and embryos cultured in the presence of pBMSCs subjected to 40 MPa HHP. In conclusion, HHP does not induce apoptosis in pBMSCs. The obtained results of the blastocysts cocultured in vitro with pBMSCs (HHP-treated and untreated cells) imply that coculture with pBMSCs has a negative impact on the developmental rates of blastocysts.

Human adipose tissue-derived stem cells inhibit the activity of keloid fibroblasts and fibrosis in a keloid model by paracrine signaling

BACKGROUND

Human adipose tissue-derived mesenchymal stem cells (ASCs) have potential utility as modulators of the regeneration of tissue that is inflamed or scarred secondary to injuries such as burns or trauma. However, the effect of ASCs on one particular type of scarring, keloidal disease, remains unknown. The absence of an optimal model for investigation has hindered the development of an effective therapy using ASCs for keloids.

OBJECTIVE

To investigate the influence of ASCs on angiogenesis, extracellular matrix deposition, and inflammatory cell influx in keloids.

METHODS

We analyzed the proliferation, migration, and apoptosis of human keloid-derived fibroblasts treated with a starvation-induced, conditioned medium from ASCs (ASCs-CM). This was achieved by Brdu proliferation assay, a validated co-culture migration assay, and flow cytometry, respectively. To assess the change in phenotype to a pro-fibrotic state, fibroblasts were analyzed by real-time PCR and contraction assay. A keloid implantation animal model was used to assess the paracrine effect of ASCs histochemically and immunohistochemically on scar morphology, collagen deposition, inflammatory cell composition, and blood vessel density. In tandem, an antibody-based array was used to identify protein concentration in the presence of ASCs-CM at time point 0, 24, and 48h.

RESULTS

ASCs-CM inhibited the proliferation and collagen synthesis of human keloid-derived fibroblasts. ASCs-CM was associated with reduced inflammation and fibrosis in the keloid implantation model. Thirty-four cytokines were differentially regulated by ASCs-CM at 24h. These included molecules associated with apoptosis, matrix metalloproteases, and their inhibitors. The same molecules were present at relatively higher concentrations at the 48h timepoint.

CONCLUSION

These results suggest that ASCs are associated with the inhibition of fibrosis in keloids by a paracrine effect. This phenomenon may have utility as a therapeutic approach in the clinical environment.

Inhibition of penile tunica albuginea myofibroblasts activity by adipose-derived stem cells

The activation of tunica albuginea myofibroblasts (MFs) serves an essential role in Peyronie's disease (PD). Increasing evidence has reported that adipose tissue-derived stem cells (ADSCs) have been demonstrated to attenuate the symptoms of PD in animal models. However, the mechanisms of the antifibrotic effects of ADSCs in PD remain to be fully elucidated. In the present study, the inhibitory effects and possible mechanism of ADSCs on the activation of MFs derived from rat penile tunica albuginea were investigated. ADSCs were obtained from the paratesticular fat of Sprague Dawley rats. MFs were transformed from rat penile tunica albuginea fibroblasts through stimulation with 5 ng/ml tumor growth factor-β1. Transwell cell cultures were adopted for co-culture of ADSCs and MFs. Western blot analysis was used to assess changes in the expression levels of α smooth muscle actin (αSMA), collagen I, phosphorylated (p)-SMAD family member 2 (Smad2), Smad2, ras homolog family member A (RhoA), Rho associated coiled-coil containing protein kinase (ROCK)1 and ROCK2, caspase3, caspase9, and matrix metalloproteinases (MMPs). Collagen gel assays were used to assess cell contractility. Additionally, the concentration of hydroxyproline in the culture medium was detected using commercially available kits. It was demonstrated that ADSCs reduced the expression of αSMA and collagen I of MFs. Furthermore, p-Smad2, RhoA, ROCK1 and ROCK2 expression was significantly reduced in the MFs+ADSCs group compared with that in the MFs-only culture, while the expression of MMPs (MMP2, MMP3, MMP9 and MMP13) and caspases (caspase3 and caspase9) was upregulated. In addition, ADSCs were able to downregulate the concentration of hydroxyproline in the culture medium of MFs and reverse the contraction of MFs. Collectively, these results suggested that ADSCs inhibited the activation of MFs, decreased collagen production, and suppressed the contraction of myofibroblasts, via Smad and RhoA/ROCK signaling pathways. Furthermore, ADSCs reduced the deposition of collagen and promoted the apoptosis of MFs via MMPs, and caspases. Accordingly, the application of ADSCs may provide a novel therapeutic strategy for PD.

Umbilical cord-derived mesenchymal stem cell extracts reduce colitis in mice by re-polarizing intestinal macrophages

Human umbilical cord mesenchymal stem cells (hUC-MSCs), originating in Wharton’s jelly, are multipotent stem cells that home to damaged tissues and can modulate the immune system. We examined whether administering extracts of MSCs (MSC-Ex) instead of MSCs could augment the beneficial effects of MSC therapy by overcoming the low homing efficiency of MSCs systemically administered in inflammatory bowel diseases (IBD). Dextran sodium sulfate-induced colitis model was established in C57BL/6 mice, and MSC-Ex was administered intraperitoneally. MSC-Ex reduced colitis, disease activity index (DAI), and histological colitis scores, and increased the body weight. Treatment with MSC-Ex completely blocked the induction of inflammatory cytokines, which were strongly detected in mice with colitis. MSC-Ex shifted the macrophage functional phenotype from M1 to M2 by decreasing the levels of MCP1, CXCL9, and iNOS, but increasing the levels of IL-10, LIGHT, CCL1, and Arg-1. MSC-Ex recovered the destruction of the epithelial barrier in the differentiated Caco-2 cells in vitro. Treatment with MSC-Ex was more potent than that with MSC in reducing DAI, the histological score, and nitrite levels. These data strongly support that MSC-Ex treatment can be a potent approach to overcome severe refractory IBD.

Inhibiting function of human fetal dermal mesenchymal stem cells on bioactivities of keloid fibroblasts

BACKGROUND

Keloid is one kind of benign skin disease caused by hyperplasia of fibroblasts and collagen fibrils. It is refractory due to the lack of an effective treatment at present, which puts pressure on seeking a new therapeutic regimen. Mesenchymal stem cells (MSCs) from fetal skin are considered to play a crucial role in scarless healing. Nevertheless, the efficacy of them in keloid disorders remains poorly understood.

METHODS

Keloid fibroblasts (KFs), human adult dermal fibroblasts (ADFs), and human fetal dermal mesenchymal stem cells (FDMSCs) were isolated to single cells and cultured in Dulbecco's modified Eagle's medium (DMEM). ADFs and FDMSCs were used to generate ADF-conditioned medium (A-CM) and FDMSC-conditioned medium (F-CM). The effects of A-CM and F-CM on KFs were tested using MTT assay, BrdU assay, TUNEL assay, quantitative polymerase chain reaction, Western blot, and annexin V-FITC/PI binding assay,.

RESULTS

FDMSCs inhibited the bioactivity of KFs, downregulated the expression of the antiapoptotic protein BCL-2, and upregulated the expression of the proapoptotic protein BAX of KFs by secreting some soluble substances, thus accelerating the apoptosis of KFs.

CONCLUSION

F-CM induces apoptosis of KFs, providing a novel treatment strategy for keloid disorders.

The Role of Phytochemicals in the Inflammatory Phase of Wound Healing

Historically, plant-based products have been the basis of medicine since before the advent of modern Western medicine. Wound dressings made of honey, curcumin and other phytochemical-rich compounds have been traditionally used. Recently, the mechanisms behind many of these traditional therapies have come to light. In this review, we show that in the context of wound healing, there is a global theme of anti-inflammatory and antioxidant phytochemicals in traditional medicine. Although promising, we discuss the limitations of using some of these phytochemicals in order to warrant more research, ideally in randomized clinical trial settings.

Acellular Gelatinous Material of Human Umbilical Cord Enhances Wound Healing: A Candidate Remedy for Deficient Wound Healing

Impaired wound healing is a severe clinical challenge and research into finding effective wound healing strategies is underway as there is no ideal treatment. Gelatinous material from the umbilical cord called Wharton's jelly is a valuable source of mesenchymal stem cells which have been shown to aid wound healing. While the cellular component of Wharton's jelly has been the subject of extensive research during the last few years, little is known about the de-cellularized jelly material of the umbilical cord. This is important as they are native niche of stem cells. We have isolated Wharton's jelly from umbilical cords and then fractionated acellular gelatinous Wharton's jelly (AGWJ). Here, we show for the first time that AGWJ enhances wound healing in vitro as well as in vivo for wounds in a murine model. In vivo staining of the wounds revealed a smaller wound length in the AGWJ treated wounds in comparison to control treatment by enhancing cell migration and differentiation. AGWJ significantly enhanced fibroblast cell migration in vitro. Aside from cell migration, AGWJ changed the cell morphology of fibroblasts to a more elongated phenotype, characteristic of myofibroblasts, confirmed by upregulation of alpha smooth muscle actin using immunoblotting. AGWJ treatment of wounds led to accelerated differentiation of cells into myofibroblasts, shortening the proliferation phase of wound healing. This data provides support for a novel wound healing remedy using AGWJ. AGWJ being native biological, cost effective and abundantly available globally, makes it a highly promising treatment option for wound dressing and skin regeneration.

Bioactive molecules derived from umbilical cord mesenchymal stem cells

Umbilical cord mesenchymal stem cells (UCMSCs) retain their intrinsic stem cell potential while at the same time displaying high proliferation rates, powerful differentiation capacity, and low immunogenicity. They can also secrete multiple bioactive molecules that exert specific physiological functions. Thus, UCMSCs represent excellent candidates for cell therapy in regenerative medicine and tissue engineering. Abundant preclinical research on different disease models has shown that UCMSCs can accelerate wound or nerve damage recovery and suppress tumor progression. In fact, UCMSCs are thought to possess a higher therapeutic potential than MSCs derived from other tissues. Increasing evidence suggests that the mechanism underlying UCSMCs efficacy depends mostly on cell secretions, in contrast to the early paradigm of cell replacement and differentiation. In this review, we discuss UCMSCs biological characteristics, their secretome-based therapeutic mechanism, and potential applications.

Adipose tissue-derived stem cells suppress hypertrophic scar fibrosis via the p38/MAPK signaling pathway

BACKGROUND

Hypertrophic scars (HS) generally occur after injury to the deep layers of the dermis, resulting in functional deficiency for patients. Growing evidence has been identified that the supernatant of adipose tissue-derived stem cells (ADSCs) significantly ameliorates fibrosis of different tissues, but limited attention has been paid to its efficacy on attenuating skin fibrosis. In this study, we explored the effect and possible mechanism of ADSC-conditioned medium (ADSC-CM) on HS.

METHOD

Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting were used to detect the expression of collagen I (Col1), collagen III (Col3), and α-smooth muscle actin (α-SMA) after fibroblasts and cultured HS tissues were stimulated with ADSC-CM and p38 inhibitor/activator. Immunofluorescence staining was performed to test the expression of α-SMA. Masson's trichrome staining, hematoxylin and eosin (H&E) staining, and immunohistochemistry staining were carried out to assess the histological and pathological change of collagen in the BALB/c mouse excisional model. All data were analyzed by using SPSS17.0 software. Statistical analysis was performed by Student's t tests.

RESULTS

The in vitro and ex vivo study revealed ADSC-CM decreased the expression of Col1, Col3, and α-SMA. Together, thinner and orderly arranged collagen was manifested in HS tissues cultured with ADSC-CM. Dramatically, the assessed morphology showed an accelerated healing rate, less collagen deposition, and col1- and col3-positive cells in the ADSC-CM treated group. Importantly, the protein level of p-p38 was downregulated in a concentration-dependent manner in HS-derived fibroblasts with ADSC-CM treatment, which further decreased the expression of p-p38 after the application of its inhibitor, SB203580. SB203580 led to an obvious decline in the expression of Col1, Col3, and α-SMA in fibroblasts and cultured HS tissues and presented more ordered arrangement and thinner collagen fibers in BALB/c mice. Lastly, anisomycin, an agonist of p38, upregulated the expression of fibrotic proteins and revealed more disordered structure and denser collagen fibers.

CONCLUSION

This study demonstrated that ADSC-CM could decrease collagen deposition and scar formation in in vitro, ex vivo and in vivo experiments. The regulation of the p38/MAPK signaling pathway played an important role in the process. The application of ADSC-CM may provide a novel therapeutic strategy for HS treatment, and the anti-scarring effect can be achieved by inhibition of the p38/MAPK signaling pathway.

Will stem cells bring hope to pathological skin scar treatment?

Pathological skin scars, such as keloids, aesthetically and psychosocially affect patients. The quest for scar reduction and the increasing recognition of patient satisfaction has led to the continued exploration of scar treatment. Stem cells are a promising source for tissue repair and regeneration. The multi-potency and secretory functions of these cells could offer possible treatments for pathological scars and have been examined in recent studies. Here, we analyze the factors that influence the formation of pathological skin scars, summarize recent research on pathological scar treatment with stem cells and elaborate on the possible mechanisms of this treatment. Additionally, other effects of stem cell treatments are also presented while evaluating potential side effects of stem cell-based pathological scar treatments. Thus, this review may provide meaningful guidance in the clinic for scar treatments with stem cells.

Bone marrow derived mesenchymal stem cells inhibit the proliferative and profibrotic phenotype of hypertrophic scar fibroblasts and keloid fibroblasts through paracrine signaling

BACKGROUND

Hypertrophic scars and keloids, characterized by over-proliferation of fibroblasts and aberrant formation of the extracellular matrix (ECM), are considered fibrotic diseases. Accumulating evidence indicates that mesenchymal stem cells (MSCs) promote scar-free wound healing and inhibit fibrotic tissue formation, making them a potentially effective therapeutic treatment for hypertrophic scars and keloids.

OBJECTIVE

To investigate the paracrine effects of bone marrow derived MSCs (BMSCs) on the biological behavior of hypertrophic scar fibroblasts (HSFs) and keloid fibroblasts (KFs).

METHODS

Proliferative and profibrotic phenotype changes of the fibroblasts were analyzed by immunofluorescence staining, in-cell western blot, and real-time PCR.

RESULTS

BMSC-conditioned medium inhibited HSF and KF proliferation and migration, but did not induce apoptosis. Interestingly, normal skin fibroblast-conditioned medium exhibited no inhibitory effects on HSF or KF proliferation and migration. Furthermore, BMSC-conditioned medium significantly decreased expression of profibrotic genes, including connective tissue growth factor, plasminogen activator inhibitor-1, transforming growth factor-β1, and transforming growth factor-β2, in HSFs and KFs at both transcriptional and translational levels. In contrast, the expression of antifibrotic genes, such as transforming growth factor-β3 and decorin, was substantially enhanced under the same culture conditions. Finally, we observed that BMSC-conditioned medium suppressed the ECM synthesis in HSFs and KFs, as indicated by decreased expression of collagen I and fibronectin and low levels of hydroxyproline in cell culture supernatant.

CONCLUSION

These findings suggest that BMSCs attenuate the proliferative and profibrotic phenotype associated with HSFs and KFs and inhibit ECM synthesis through a paracrine signaling mechanism.

Chemokine-Like Factor 1 (CKLF-1) is Overexpressed in Keloid Patients: A Potential Indicating Factor for Keloid-Predisposed Individuals

Chemokine-like factor 1 (CKLF-1) is a novel cytokine which have a crucial role in immune and inflammatory responses. In this study, the expression level of CKLF-1 was measured to assess the difference between keloid patients and people without keloid. Fifty samples were taken from 30 patients: 10 keloid patients; 10 scar patients; and 10 patients without obvious scarring. Patients were randomly selected from the hospitalized patients of Peking Union Medical College Hospital from September 2013 to July 2015. Five groups of samples were established: keloid samples from keloid patients (K); normal skin samples from keloid patients (KS); scar samples from scar patients (C); normal skin samples from scar patients (CS); and normal skin samples from patients without obvious scarring (S). Hematoxylin and eosin (H&E) staining was used to observe morphological changes. CKLF-1, IL-6, IL-8, IL-18, and TGF-β were detected by immunohistochemical and western blot technology. The expression of CKLF-1's mRNA was also measured by the real-time quantitative polymerase chain reaction (RT-qPCR). Compared to the K group, the other 4 groups presented significantly less inflammatory infiltration and lower expression levels of CKLF-1, IL-6, IL-8, IL-18, and TGF-β. Among the 3 normal skin groups, the expression level of CKLF-1 was significantly higher in the KS group than in the CS or S group. The mRNA expression was also obvious in the K and KS groups. CKLF-1 and other inflammatory factors were overexpressed in the samples from keloid patients, indicating that the formation of keloid may be related to inflammation and that CKLF-1 may play an important role in this process.

Mesenchymal stem cells promote colorectal cancer progression through AMPK/mTOR-mediated NF-κB activation

Mesenchymal stem cells (MSCs) exert a tumor-promoting effect in a variety of human cancers. This study was designed to identify the molecular mechanisms related to the tumor-promoting effect of MSCs in colorectal cancer. In vitro analysis of colorectal cancer cell lines cultured in MSC conditioned media (MSC-CM) showed that MSC-CM significantly promoted the progression of the cancer cells by enhancing cell proliferation, migration and colony formation. The tumorigenic effect of MSC-CM was attributed to altered expression of cell cycle regulatory proteins and inhibition of apoptosis. Furthermore, MSC-CM induced high level expression of a number of pluripotency factors in the cancer cells. ELISAs revealed MSC-CM contained higher levels of IL-6 and IL-8, which are associated with the progression of cancer. Moreover, MSC-CM downregulated AMPK mRNA and protein phosphorylation, but upregulated mTOR mRNA and protein phosphorylation. The NF-κB pathway was activated after addition of MSC-CM. An in vivo model in Balb/C mice confirmed the ability of MSC-CM to promote the invasion and proliferation of colorectal cancer cells. This study indicates that MSCs promote the progression of colorectal cancer via AMPK/mTOR-mediated NF-κB activation.

Alternative Mechanism for White Adipose Tissue Lipolysis after Thermal Injury

Extensively burned patients often suffer from sepsis, a complication that enhances postburn hypermetabolism and contributes to increased incidence of multiple organ failure, morbidity and mortality. Despite the clinical importance of burn sepsis, the molecular and cellular mechanisms of such infection-related metabolic derangements and organ dysfunction are still largely unknown. We recently found that upon endoplasmic reticulum (ER) stress, the white adipose tissue (WAT) interacts with the liver via inflammatory and metabolic signals leading to profound hepatic alterations, including hepatocyte apoptosis and hepatic fatty infiltration. We therefore hypothesized that burn plus infection causes an increase in lipolysis of WAT after major burn, partially through induction of ER stress, contributing to hyperlipidemia and profound hepatic lipid infiltration. We used a two-hit rat model of 60% total body surface area scald burn, followed by intraperitoneal (IP) injection of Pseudomonas Aeruginosa-derived lipopolysaccharide (LPS) 3 d postburn. One day later, animals were euthanized and liver and epididymal WAT (EWAT) samples were collected for gene expression, protein analysis and histological study of inflammasome activation, ER stress, apoptosis and lipid metabolism. Our results showed that burn plus LPS profoundly increased lipolysis in WAT associated with significantly increased hepatic lipid infiltration. Burn plus LPS augmented ER stress by upregulating CHOP and activating ATF6, inducing NLRP3 inflammasome activation and leading to increased apoptosis and lipolysis in WAT with a distinct enzymatic mechanism related to inhibition of AMPK signaling. In conclusion, burn sepsis causes profound alterations in WAT and liver that are associated with changes in organ function and structure.

Stem Cell-Based Therapeutics to Improve Wound Healing

Issues surrounding wound healing have garnered deep scientific interest as well as booming financial markets invested in novel wound therapies. Much progress has been made in the field, but it is unsurprising to find that recent successes reveal new challenges to be addressed. With regard to wound healing, large tissue deficits, recalcitrant wounds, and pathological scar formation remain but a few of our most pressing challenges. Stem cell-based therapies have been heralded as a promising means by which to surpass current limitations in wound management. The wide differentiation potential of stem cells allows for the possibility of restoring lost or damaged tissue, while their ability to immunomodulate the wound bed from afar suggests that their clinical applications need not be restricted to direct tissue formation. The clinical utility of stem cells has been demonstrated across dozens of clinical trials in chronic wound therapy, but there is hope that other aspects of wound care will inherit similar benefit. Scientific inquiry into stem cell-based wound therapy abounds in research labs around the world. While their clinical applications remain in their infancy, the heavy investment in their potential makes it a worthwhile subject to review for plastic surgeons, in terms of both their current and future applications.

Paracrine action of mesenchymal stromal cells delivered by microspheres contributes to cutaneous wound healing and prevents scar formation in mice

BACKGROUND AIMS

Accumulating evidence suggests that mesenchymal stromal cells (MSCs) participate in wound healing to favor tissue regeneration and inhibit fibrotic tissue formation. However, the evidence of MSCs to suppress cutaneous scar is extremely rare, and the mechanism remains unidentified. This study aimed to demonstrate whether MSCs-as the result of their paracrine actions on damaged tissues-would accelerate wound healing and prevent cutaneous fibrosis.

METHODS

For efficient delivery of MSCs to skin wounds, microspheres were used to maintain MSC potency. Whether MSCs can accelerate wound healing and alleviate cutaneous fibrosis through paracrine action was investigated with the use of a Transwell co-culture system in vitro and a murine model in vivo.

RESULTS

MSCs cultured on gelatin microspheres fully retained their cell surface marker expression profile, proliferation, differentiation and paracrine potential. Co-cultures of MSCs and fibroblasts indicated that the benefits of MSCs on suppressing fibroblast proliferation and its fibrotic behavior induced by inflammatory cytokines probably were caused by paracrine actions. Importantly, microspheres successfully delivered MSCs into wound margins and significantly accelerated wound healing and concomitantly reduced the fibrotic activities of cells within the wounds and excessive accumulation of extracellular matrix as well as the transforming growth factor-β1/transforming growth factor-β3 ratio.

CONCLUSIONS

This study provides insight into what we believe to be a previously undescribed, multifaceted role of MSC-released protein in reducing cutaneous fibrotic formation. Paracrine action of MSCs delivered by microspheres may thus qualify as a promising strategy to enhance tissue repair and to prevent excessive fibrosis during cutaneous wound healing.

In vitro augmentation of mesenchymal stem cells viability in stressful microenvironments : In vitro augmentation of mesenchymal stem cells viability

Mesenchymal stem cells (MSCs) are under intensive investigation for use in cell-based therapies because their differentiation abilities, immunomodulatory effects, and homing properties offer potential for significantly augmenting regenerative capacity of many tissues. Nevertheless, major impediments to their therapeutic application, such as low proliferation and survival rates remain as obstacles to broad clinical use of MSCs. Another major challenge to evolution of MSC-based therapies is functional degradation of these cells as a result of their exposure to oxidative stressors during isolation. Indeed, oxidative stress-mediated MSC depletion occurs due to inflammatory processes associated with chemotherapy, radiotherapy, and expression of pro-apoptotic factors, and the microenvironment of damaged tissue in patients receiving MSC therapy is typically therapeutic not favorable to their survival. For this reason, any strategies that enhance the viability and proliferative capacity of MSCs associated with their therapeutic use are of great value. Here, recent strategies used by various researchers to improve MSC allograft function are reviewed, with particular focus on in vitro conditioning of MSCs in preparation for clinical application. Preconditioning, genetic manipulation, and optimization of MSC culture conditions are some examples of the methodologies described in the present article, along with novel strategies such as treatment of MSCs with secretome and MSC-derived microvesicles. This topic material is likely to find value as a guide for both research and clinical use of MSC allografts and for improvement of the value that use of these cells brings to health care.