Stem Cells and Healing: Impact on Inflammation

A Rheological Study on the Effect of Tethering Pro- and Anti-Inflammatory Cytokines into Hydrogels on Human Mesenchymal Stem Cell Migration, Degradation, and Morphology

Polymer-peptide hydrogels are being designed as implantable materials that deliver human mesenchymal stem cells (hMSCs) to treat wounds. Most wounds can progress through the healing process without intervention. During the normal healing process, cytokines are released from the wound to create a concentration gradient, which causes directed cell migration from the native niche to the wound site. Our work takes inspiration from this process and uniformly tethers cytokines into the scaffold to measure changes in cell-mediated degradation and motility. This is the first step in designing cytokine concentration gradients into the material to direct cell migration. We measure changes in rheological properties, encapsulated cell-mediated pericellular degradation and migration in a hydrogel scaffold with covalently tethered cytokines, either tumor necrosis factor-α (TNF-α) or transforming growth factor-β (TGF-β). TNF-α is expressed in early stages of wound healing causing an inflammatory response. TGF-β is released in later stages of wound healing causing an anti-inflammatory response in the surrounding tissue. Both cytokines cause directed cell migration. We measure no statistically significant difference in modulus or the critical relaxation exponent when tethering either cytokine in the polymeric network without encapsulated hMSCs. This indicates that the scaffold structure and rheology is unchanged by the addition of tethered cytokines. Increases in hMSC motility, morphology and cell-mediated degradation are measured using a combination of multiple particle tracking microrheology (MPT) and live-cell imaging in hydrogels with tethered cytokines. We measure that tethering TNF-α into the hydrogel increases cellular remodeling on earlier days postencapsulation and tethering TGF-β into the scaffold increases cellular remodeling on later days. We measure tethering either TGF-β or TNF-α enhances cell stretching and, subsequently, migration. This work provides rheological characterization that can be used to design new materials that present chemical cues in the pericellular region to direct cell migration.

Deciphering the crosstalk between inflammation and biofilm in chronic wound healing: Phytocompounds loaded bionanomaterials as therapeutics

In terms of the economics and public health, chronic wounds exert a significant detrimental impact on the health care system. Bacterial infections, which cause the formation of highly resistant biofilms that elude standard antibiotics, are the main cause of chronic, non-healing wounds. Numerous studies have shown that phytochemicals are effective in treating a variety of diseases, and traditional medicinal plants often include important chemical groups such alkaloids, phenolics, tannins, terpenes, steroids, flavonoids, glycosides, and fatty acids. These substances are essential for scavenging free radicals which helps in reducing inflammation, fending off infections, and hastening the healing of wounds. Bacterial species can survive in chronic wound conditions because biofilms employ quorum sensing as a communication technique which regulates the expression of virulence components. Fortunately, several phytochemicals have anti-QS characteristics that efficiently block QS pathways, prevent drug-resistant strains, and reduce biofilm development in chronic wounds. This review emphasizes the potential of phytocompounds as crucial agents for alleviating bacterial infections and promoting wound healing by reducing the inflammation in chronic wounds, exhibiting potential avenues for future therapeutic approaches to mitigate the healthcare burden provided by these challenging conditions.

The role of orthobiologics in chronic wound healing

Chronic wounds, characterized by prolonged healing processes, pose a significant medical challenge with multifaceted aetiologies, including local and systemic factors. Here, it explores the complex pathogenesis of chronic wounds, emphasizing the disruption in the normal phases of wound healing, particularly the inflammatory phase, leading to an imbalance in extracellular matrix (ECM) dynamics and persistent inflammation. Senescent cell populations further contribute to impaired wound healing in chronic lesions. Traditional medical management focuses on addressing underlying causes, but many chronic wounds resist to conventional treatments, necessitating innovative approaches. Recent attention has turned to autologous orthobiologics, such as platelet-rich plasma (PRP), platelet-rich fibrin (PRF) and mesenchymal stem cells (MSCs), as potential regenerative interventions. These biologically derived materials, including bone marrow aspirate/concentrate (BMA/BMAC) and adipose tissue-derived stem cells (ADSCs), exhibit promising cytokine content and regenerative potential. MSCs, in particular, have emerged as key players in wound healing, influencing inflammation and promoting tissue regeneration. This paper reviews relevant scientific literature regarding basic science and brings real-world evidence regarding the use of orthobiologics in the treatment of chronic wounds, irrespective of aetiology. The discussion highlights the regenerative properties of PRP, PRF, BMA, BMAC and SVF, showcasing their potential to enhance wound healing. Despite advancements, further research is essential to elucidate the specific roles of each orthobiologic and determine optimal applications for different wound types. The conclusion underscores the evolving landscape in chronic wound management, with a call for more comprehensive studies to refine treatment strategies and maximize the benefits of regenerative medicine.

Comparing the Effects of Intramuscular Injections of Dexamethasone and Ketorolac Tromethamine on Post-treatment Endodontic Pain: An In Vivo Study

BACKGROUND AND OBJECTIVES

Pain is the primary reason dental patients seek endodontic therapy. Post-treatment endodontic discomfort is a sequelae of periapical inflammation and anti-inflammatory drugs such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) would be reasonable therapy options. The purpose of this study was to compare and assess the efficacy of intramuscular injections of dexamethasone and ketorolac tromethamine versus placebo in reducing post-treatment endodontic pain in individuals undergoing root canal treatment.

METHODOLOGY

Patients diagnosed with symptomatic irreversible pulpitis were selected. Nonsurgical endodontic therapy was carried out in a single visit. After completion of the root canal therapy, the patients were randomly assigned to one of the three groups for intramuscular drug administration. In group 1, 2 ml of sterile saline was administered, in group 2, 1 ml of 4 mg dexamethasone was administered; and in group 3, 1 ml of 30 mg ketorolac tromethamine was administered. Preoperative and postoperative pain intensity was measured by a verbal rating scale. Postoperatively, the incidence and severity of pain were recorded after four, 24, and 48 hours.

RESULTS

All three groups showed a highly statistically significant reduction in pain scores when compared to preoperative levels. At the end of four hours, dexamethasone and ketorolac tromethamine showed highly significant results. Dexamethasone significantly reduced pain after 24 hours when compared to ketorolac and placebo groups. At the conclusion of 48 hours, all three groups experienced a gradual decrease in pain levels.

CONCLUSION

Effective and complete debridement of infected root canal system provides predictable gradual reduction of post-endodontic pain.

Inhibition of the CoREST Repressor Complex Promotes Wound Re-Epithelialization through the Regulation of Keratinocyte Migration

Wound healing is a complex process involving phases of hemostasis, inflammation, proliferation, and remodeling. The regenerative process in the skin requires coordination between many regulators, including signaling molecules, transcription factors, and the epigenetic machinery. In this study, we show that chromatin regulators HDAC1 and LSD1, key components of the CoREST repressor complex, are upregulated in the regenerating epidermis during wound repair. We also show that corin, a synthetic dual inhibitor of the CoREST complex and HDAC1/LSD1 activities, significantly accelerates wound closure through enhanced re-epithelialization in a mouse tail wound model. Acetylated H3K9 (methylation of histone H3 at lysine 9) expression, a histone modification targeted by HDAC1, is increased in keratinocytes after topical treatment with 100 nM and 1 μM of corin. In vitro experiments demonstrate that corin promotes migration and inhibits the proliferation of human keratinocytes. Furthermore, expression levels of genes promoting keratinocyte migration, such as AREG, CD24, EPHB2, ITGAX, PTGS, SCT1, SERPINB2, SERPINE1, SLPI, SNAI2, and TWIST, increased in keratinocytes treated with corin. These data demonstrate that dual inhibition of class I histone deacetylases and LSD1 by corin may serve as a new approach for promoting wound re-epithelialization and provide a platform for further applications of corin for the treatment of chronic wounds.

The multifactorial nature of healthy brain ageing: Brain changes, functional decline and protective factors

As the global population faces a progressive shift towards a higher median age, understanding the mechanisms underlying healthy brain ageing has become of paramount importance for the preservation of cognitive abilities. The first part of the present review aims to provide a comprehensive look at the anatomical changes the healthy brain endures with advanced age, while also summarizing up to date findings on modifiable risk factors to support a healthy ageing process. Subsequently, we describe the typical cognitive profile displayed by healthy older adults, conceptualizing the well-established age-related decline as an impairment of four main cognitive factors and relating them to their neural substrate previously described; different cognitive trajectories displayed by typical Alzheimer's Disease patients and successful agers with a high cognitive reserve are discussed. Finally, potential effective interventions and protective strategies to promote cognitive reserve and defer cognitive decline are reviewed and proposed.

A biotin-stabilized HKUST-1/ADM scaffold for facilitating MSC endothelial differentiation and vascularization in diabetic wound healing

Inadequate angiogenesis in diabetic wound healing has been identified as one of the most difficult issues to treat. Copper ions (Cu²⁺) have been confirmed to stimulate angiogenesis; nevertheless, the rapid rise in non-physiological Cu²⁺ concentrations increases the danger of ion poisoning. For the first time, biotin was used to stabilize a copper-based metal-organic framework (HKUST-1) to change its hydrophobicity and achieve sustained release of Cu²⁺. The inability to offer a suitable area for the dynamic interaction between cells and growth factors still restricts the use of nanomaterials for the regeneration of injured skin in diabetes. Acellular dermal matrix (ADM) scaffolds are collagen fibers with natural spatial tissue that can create a biological "niche" for cell attachment and growth. In this study, biotin-stabilized HKUST-1 (B-HKUST-1) nanoparticles were modified with an ADM to form a novel scaffold (ADM-B-HKUST-1). Notably, Cu²⁺ and mesenchymal stem cells (MSCs) released by the composite scaffold may synergistically promote MSC adhesion, proliferation and endothelial differentiation by upregulating the expression of transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (α-SMA). Overall, the ADM-B-HKUST1 scaffold combines the dual advantages of the sustained release of Cu²⁺ and creating a biological "niche" can provide a potential strategy for enhancing angiogenesis and promoting diabetic wound healing.

MicroRNA-139-5p mediates BMSCs impairment in diabetes by targeting HOXA9/c-Fos

The properties and functions of BMSCs were altered by the diabetic microenvironment, and its mechanism was not very clear. In recent years, the regulation of the function of BMSCs by microRNA has become a research hotspot, meanwhile, HOX genes also have been focused on and involved in multiple functions of stem cells. In this study, we investigated the role of miR-139-5p in diabetes-induced BMSC impairment. Since HOXA9 may be a target gene of miR-139-5p, we speculated that miR-139-5p/HOXA9 might be involved in regulating the biological characteristics and the function of BMSCs in diabetes. We demonstrated that the miR-139-5p expression was increased in BMSCs derived from STZ-induced diabetic rats. MiR-139-5p mimics were able to inhibit cell proliferation, and migration and promoted senescence and apoptosis in vitro. MiR-139-5p induced the down-regulated expression of HOXA9 and c-Fos in BMSCs derived from normal rats. Moreover, miR-139-5p inhibitors reversed the tendency in diabetic-derived BMSCs. Further, gain-and-loss function experiments indicated that miR-139-5p regulated the functions of BMSCs by targeting HOXA9 and c-Fos. In vivo wound model experiments showed that the downregulation of miR-139-5p further promoted the epithelialization and angiogenesis of diabetic BMSC-mediated skin. In conclusion, induction of miR-139-5p upregulation mediated the impairment of BMSCs through the HOXA9/c-Fos pathway in diabetic rats. Therefore, miR-139-5p/HOXA9 might be an important therapeutic target in treating diabetic BMSCs and diabetic complications in the future.

Advances in the Treatment of Partial-Thickness Cartilage Defect

Partial-thickness cartilage defects (PTCDs) of the articular surface is the most common problem in cartilage degeneration, and also one of the main pathogenesis of osteoarthritis (OA). Due to the lack of a clear diagnosis, the symptoms are often more severe when full-thickness cartilage defect (FTCDs) is present. In contrast to FTCDs and osteochondral defects (OCDs), PTCDs does not injure the subchondral bone, there is no blood supply and bone marrow exudation, and the nearby microenvironment is unsuitable for stem cells adhesion, which completely loses the ability of self-repair. Some clinical studies have shown that partial-thickness cartilage defects is as harmful as full-thickness cartilage defects. Due to the poor effect of conservative treatment, the destructive surgical treatment is not suitable for the treatment of partial-thickness cartilage defects, and the current tissue engineering strategies are not effective, so it is urgent to develop novel strategies or treatment methods to repair PTCDs. In recent years, with the interdisciplinary development of bioscience, mechanics, material science and engineering, many discoveries have been made in the repair of PTCDs. This article reviews the current status and research progress in the treatment of PTCDs from the aspects of diagnosis and modeling of PTCDs, drug therapy, tissue transplantation repair technology and tissue engineering ("bottom-up").

Measuring human mesenchymal stem cell remodeling in hydrogels with a step-change in elastic modulus

Human mesenchymal stem cells (hMSCs) are instrumental in the wound healing process. They migrate to wounds from their native niche in response to chemical signals released during the inflammatory phase of healing. At the wound, hMSCs downregulate inflammation and regulate tissue regeneration. Delivering additional hMSCs to wounds using cell-laden implantable hydrogels has the potential to improve healing outcomes and restart healing in chronic wounds. For these materials to be effective, cells must migrate from the scaffold into the native tissue. This requires cells to traverse a step-change in material properties at the implant-tissue interface. Migration of cells in material with highly varying properties is not well characterized. We measure 3D encapsulated hMSC migration and remodeling in a well-characterized hydrogel with a step-change in stiffness. This cell-degradable hydrogel is composed of 4-arm poly(ethylene glycol)-norbornene cross-linked with an enzymatically-degradable peptide. The scaffold is made with two halves of different stiffnesses separated by an interface where stiffness changes rapidly. We characterize changes in structure and rheology of the pericellular region using multiple particle tracking microrheology (MPT). MPT measures Brownian motion of embedded particles and relates it to material rheology. We measure more remodeling in the soft region of the hydrogel than the stiff region on day 1 post-encapsulation and similar remodeling everywhere on day 6. In the interface region, we measure hMSC-mediated remodeling along the interface and migration towards the stiff side of the scaffold. These results can improve materials designed for cell delivery from implants to a wound to enhance healing.

Adipose stromal vascular fraction: a promising treatment for severe burn injury

Thermal skin burn injury affects both adults and children globally. Severe burn injury affects a patient's life psychologically, cosmetically, and socially. The pathophysiology of burn injury is well known. Due to the complexity of burn pathophysiology, the development of specific treatment aiding in tissue regeneration is required. Treatment of burn injury depends on burn severity, size of the burn and availability of donor site. Burn healing requires biochemical and cellular events to ensure better cell response to biochemical signals of the healing process. This led to the consideration of using cell therapy for severe burn injury. Adult mesenchymal stem cells have become a therapeutic option because of their ability for self-renewal and differentiation. Adipose stromal vascular fraction (SVF), isolated from adipose tissues, is a heterogeneous cell population that contains adipose-derived stromal/stem cells (ADSC), stromal, endothelial, hematopoietic and pericytic lineages. SVF isolation has advantages over other types of cells; such as heterogeneity of cells, lower invasive extraction procedure, high yield of cells, and fast and easy isolation. Therefore, SVF has many characteristics that enable them to be a therapeutic option for burn treatment. Studies have been conducted mostly in animal models to investigate their therapeutic potential for burn injury. They can be used alone or in combination with other treatment options. Treatment with both ADSCs and/or SVF enhances burn healing through increasing re-epithelization, angiogenesis and decreasing inflammation and scar formation. Research needs to be conducted for a better understanding of the SVF mechanism in burn healing and to optimize current techniques for enhanced treatment outcomes.

Senescence in chronic wounds and potential targeted therapies

Chronic wounds (e.g. diabetic wounds, pressure wounds, vascular ulcers, etc.) do not usually heal in a timely and orderly manner but rather last for years and may lead to irreversible adverse events, resulting in a substantial financial burden for patients and society. Recently, a large amount of evidence has proven that cellular senescence has a crucial influence on chronic nonhealing wounds. As a defensive mechanism, cell senescence is a manner of cell-cycle arrest with increased secretory phenotype to resist death, preventing cells from stress-induced damage in cancer and noncancer diseases. A growing amount of research has advanced the perception of cell senescence in various chronic wounds and focuses on pathological and physiological processes and therapies targeting senescent cells. However, previous reviews have failed to sum up novel understandings of senescence in chronic wounds and emerging strategies targeting senescence. Herein, we discuss the characteristics and mechanisms of cellular senescence and the link between senescence and chronic wounds as well as some novel antisenescence strategies targeting other diseases that may be applied for chronic wounds.

Lipoaspirate Shows In Vitro Potential for Wound Healing

Mesenchymal stem cells (MSCs) are a promising therapy in wound healing, although extensive time and manipulation are necessary for their use. In our previous study on cartilage regeneration, we demonstrated that lipoaspirate acts as a natural scaffold for MSCs and gives rise to their spontaneous outgrowth, together with a paracrine effect on resident cells that overcome the limitations connected to MSC use. In this study, we aimed to investigate in vitro whether the microfragmented adipose tissue (lipoaspirate), obtained with Lipogems^® technology, could promote and accelerate wound healing. We showed the ability of resident cells to outgrow from the clusters of lipoaspirate encapsulated in a 3D collagen substrate as capability of repopulating a culture of human skin. Moreover, we demonstrated that the in vitro lipoaspirate paracrine effect on fibroblasts and keratinocytes proliferation, migration, and contraction rate is mediated by the release of trophic/reparative proteins. Finally, an analysis of the paracrine antibacterial effect of lipoaspirate proved its ability to secrete antibacterial factors and its ability to modulate their secretion in culture media based on a bacterial stimulus. The results suggest that lipoaspirate may be a promising approach in wound healing showing in vitro regenerative and antibacterial activities that could improve current therapeutic strategies.

MSCs and their exosomes: a rapidly evolving approach in the context of cutaneous wounds therapy

Currently, mesenchymal stem/stromal stem cell (MSC) therapy has become a promising option for accelerating cutaneous wound healing. In vivo reports have outlined the robust competences of MSCs to offer a solid milieu by inhibition of inflammatory reactions, which in turn, enables skin regeneration. Further, due to their great potential to stimulate angiogenesis and also facilitate matrix remodeling, MSCs hold substantial potential as future therapeutic strategies in this context. The MSCs-induced wound healing is thought to mainly rely on the secretion of a myriad of paracrine factors in addition to their direct differentiation to skin-resident cells. Besides, MSCs-derived exosomes as nanoscale and closed membrane vesicles have recently been suggested as an effective and cell-free approach to support skin regeneration, circumventing the concerns respecting direct application of MSCs. The MSCs-derived exosomes comprise molecular components including lipid, proteins, DNA, microRNA, and also mRNA, which target molecular pathways and also biological activities in recipient cells (e.g., endothelial cell, keratinocyte, and fibroblast). The secreted exosome modifies macrophage activation, stimulates angiogenesis, and instigates keratinocytes and dermal fibroblast proliferations as well as migrations concurrently regulate inherent potential of myofibroblast for adjustment of turnover of the ECM. In the present review, we will focus on the recent findings concerning the application of MSCs and their derivative exosome to support wound healing and skin regeneration, with special focus on last decade in vivo reports.

Establishing a technique for isolation and characterization of human periodontal ligament derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are extensively used in tissue regenerative procedures. One source of MSCs is the periodontal ligament (PDL) of teeth. Isolation of MSCs from extracted teeth is reasonably simple, being less invasive and presenting fewer ethical concerns than does the harvesting of MSC’s from other sites. The objectives of this study were to isolate and characterize the PDL stem cells (PDLSC) from healthy adults’ extracted teeth and then to characterize them by comparing them with bone-marrow derived MSCs (BMMSC).

Methods

The PDL tissue was scraped from the roots of freshly extracted teeth to enzymatically digest using collagenase. The cells were sub-cultured. Flow-cytometric analysis for the MSC surface-markers CD105, CD73, CD166, CD90, CD34, CD45 and HLA-DR was performed. To confirm the phenotype, total RNA was extracted to synthesize cDNA and which was then subjected to RT-PCR. The gene-expression for Oct4A, Sox2, NANOG and GAPDH was determined by gel-electrophoresis. To assess their multilineage potential, cells were cultured with osteogenic, chondrogenic and adipogenic medium and then stained by Alizarin-red, Alcian-blue and Oil-Red-O respectively. MSCs from the bone-marrow were processed similarly to serve as controls.

Results

The cells isolated from extracted teeth expanded successfully. On flow-cytometric analysis, the cells were positive for CD73, CD90, CD105, CD166 and negative for CD34, CD45 and HLA-DR. The PDLSCs expressed Oct4A, Sox2, and NANOG mRNA with GAPDH expression. Cells cultured in the osteogenic, chondrogenic and adipogenic media stained positive for Alizarin-red, Alcian-blue and Oil- Red-O respectively. The surface marker expression and the trilineage differentiation characteristics were comparable to those of the BMMSCs.

Conclusions

The periodontal ligament tissue of extracted teeth is a potential source of therapeutically useful MSCs. Harvesting them is not invasive and are a promising source of MSC as the PDLSCs showed characteristics similar to those of the highly regarded MSC’s derived from bone-marrow.

Advances in Skin Wound and Scar Repair by Polymer Scaffolds

Scars, as the result of abnormal wound-healing response after skin injury, may lead to loss of aesthetics and physical dysfunction. Current clinical strategies, such as surgical excision, laser treatment, and drug application, provide late remedies for scarring, yet it is difficult to eliminate scars. In this review, the functions, roles of multiple polymer scaffolds in wound healing and scar inhibition are explored. Polysaccharide and protein scaffolds, an analog of extracellular matrix, act as templates for cell adhesion and migration, differentiation to facilitate wound reconstruction and limit scarring. Stem cell-seeded scaffolds and growth factors-loaded scaffolds offer significant bioactive substances to improve the wound healing process. Special emphasis is placed on scaffolds that continuously release oxygen, which greatly accelerates the vascularization process and ensures graft survival, providing convincing theoretical support and great promise for scarless healing.

Acellular Scaffolds as Innovative Biomaterial Platforms for the Management of Diabetic Wounds

Diabetic wound (DW) is one of the leading complications of patients having a long history of uncontrolled diabetes. Moreover, it also imposes an economic burden on people suffering from wounds to manage the treatment. The major impending factors in the treatment of DW are infection, prolonged inflammation and decreased oxygen levels. Since these non-healing wounds are associated with an extended recovery period, the existing therapies provide treatment for a limited period only. The areas covered in this review are general sequential events of wound healing along with DW's pathophysiology, the origin of DW and success, as well as limitations of existing therapies. This systematic review's significant aspect is to highlight the fabrication, characterization and applications of various acellular scaffolds used to heal DW. In addition to that, cellular scaffolds are also described to a limited extent.

The Transient Human Thyroid Progenitor Cell: Examining the Thyroid Continuum from Stem Cell to Follicular Cell

Background: The development of the thyroid follicular cell has been well characterized as it progresses from the original stem cell, either embryonic or adult, through a series of transitions to form a differentiated and functional thyroid cell. Summary: In this review, we briefly outline what is known about this transitional process with emphasis on characterizing the thyroid progenitor stem cell by using data obtained from both in vitro and in vivo studies and both mouse and human cells. It is of particular importance to note the influence of independent factors that guide the transcriptional control of the developing thyroid cell as it is subjected to extracellular signals, often working via epigenetic changes, and initiating intrinsic transcriptional changes leading to a functional cell. Conclusion: Thyroid stem cells fall into the category of dispositional stem cells and are greatly influenced by their environment.

Hyaluronic Acid Hydrogel Microspheres for Slow Release Stem Cell Delivery

Cell therapies are hampered by a lack of available delivery systems, resulting in inconsistent outcomes in animal studies and human clinical trials. Hydrogel encapsulants offer a broad range of tunable characteristics in the design of cell delivery vehicles. The focus of the hydrogel field has been on durable encapsulants that provide long-term paracrine function of the cells. However, some cell therapies require cell-to-cell contact in order to elicit their effect. Controlled release microencapsulants would be beneficial in these situations, but appropriate polymers have not been adaptable to microsphere manufacturing because they harden too slowly. We developed and tested a novel microencapsulant formulation (acrylated hyaluronic acid: AHA) with degradation characteristics as a controlled release cell delivery vehicle. The properties of AHA microspheres were evaluated and compared to those of poly(ethylene glycol) diacrylate (PEGDA), a durable hydrogel. AHA microspheres possessed a higher swelling ratio, lower diffusion barrier, faster degradation rate, a lower storage modulus, and a larger average diameter than microspheres composed of PEGDA. Additionally, in vitro cell viability and release and short-term in vivo biocompatibility in immune competent Sprague-Dawley rats was assessed for each microsphere type. Compared to PEGDA, microspheres composed of AHA resulted in significantly less foreign body response in vivo as measured by a lack of cellularity or fibrotic ring in the surrounding tissue and no cellular infiltration into the microsphere. This study illustrates the potential of AHA microspheres as a degradable cell delivery system with superior encapsulated cell viability and biocompatibility with the surrounding tissue.

Regenerative Effects of Hypoxia Primed Flowable Placental Formulation in Muscle and Dermal Injury

The placental tissue, due to its angiogenic, anti-inflammatory, antioxidative, antimicrobial, and anti-fibrotic properties, has become a compelling source towards a solution for several indications in regenerative medicine. However, methods to enhance and capture the therapeutic properties with formulations that can further the applications of viable placental tissue have not been explored. In this study, we investigated the regenerative effects of a hypoxia primed flowable placental formulation (FPF), composed of amnion/chorion and umbilical tissue, in two in vivo injury models. Laser Doppler data from rodent ischemia hindlimbs treated with FPF revealed significant tissue perfusion improvements compared to control ischemic hindlimbs. To further corroborate FPF’s effects, we used a rodent ischemic bipedicle skin flap wound model. FPF treatment significantly increased the rate of wound closure and the quality of wound healing. FPF-treated wounds displayed reduced inflammation and an increase in angiogenesis. Furthermore, quantitative PCR and next-generation sequencing analysis confirmed these changes in the FPF-treated group at both the gene and transcriptional level. The observed modulation in miRNAs was associated with angiogenesis, regulation of inflammatory microenvironment, cell migration and apoptosis, reactive oxygen species generation, and restoring epithelial barrier function, all processes involved in impaired tissue healing. Taken together, these data validate the tissue regenerative properties of the flowable placental formulation configuration tested.

Implantation of cryopreserved umbilical cord allograft in hard-to-heal foot wounds: a retrospective study

OBJECTIVE

The objective of this study was to assess the clinical effectiveness of surgically implanted cryopreserved human umbilical cord allograft in treating hard-to-heal wounds with and without osteomyelitis.

METHOD

In this single-centre, retrospective investigation, wounds (average size 6.9±10.1cm²) were included for analysis that had failed prior standard wound care for an average of 14.4±8.0 weeks.

RESULTS

After surgical implantation of cryopreserved umbilical cord between the deep tissue planes, 20 (95%) of the 21 wounds included in the study achieved complete closure in a median time of 7.8 weeks (range: 1-68) despite presence of residual osteomyelitis in 15 cases. A total of 12 wounds (57.1%) healed by 12 weeks, and 16 (76.2%) wounds healed by 24 weeks. A patient who presented with a limb-threatening calcaneal ulcer that was complicated by osteomyelitis at the time of treatment required subsequent amputation. No adverse events or complications related to cryopreserved umbilical cord were observed.

CONCLUSION

The results suggest that surgical implantation of cryopreserved umbilical cord allograft may be a safe and effective treatment in improving healing of hard-to-heal wounds. Further prospective, randomised controlled trials are warranted.

Soft Tissue Manipulation May Attenuate Inflammation, Modulate Pain, and Improve Gait in Conscious Rodents With Induced Low Back Pain

INTRODUCTION

Low back pain (LBP) is common in warfighters. Noninvasive interventions are necessary to expedite return-to-function. Soft tissue manipulation, for example, massage, is a method used to treat LBP. Instrument-assisted soft tissue manipulation (IASTM) uses a rigid device to mobilize the tissue. This study explored the effects of IASTM on pain, function, and biomarkers.

METHODS

Sprague-Dawley rats (n = 44) were randomized to groups (n = 6/grp): (A) cage control; (B) 3 days (3d) postinjury (inj), untreated; (C) 3d inj, < 30-minute post-IASTM treatment; (D) 3d inj, 2 hours (2h) post-IASTM; (E) 14 days (14d) inj, untreated; (F) 14d inj, < 30-minute post-IASTM; and (G) 14d inj, 2h post-IASTM. Researchers induced unilateral LBP in Sprague-Dawley rats using complete Freund's adjuvant injection. Conscious rodents received IASTM for 5 min/session once at 3 days or 3×/week × 2weeks (6× total) over 14 days. Biomarker plasma levels were determined in all groups, while behavioral outcomes were assessed in two groups, D and G, at three time points: before injury, pre-, and post-IASTM treatment. Circulating mesenchymal stem cell levels were assessed using flow cytometry and cytokine plasma levels assayed.

RESULTS

The back pressure pain threshold (PPT) lowered bilaterally at 3 days postinjury (P < .05), suggesting increased pain sensitivity. IASTM treatment lowered PPT more on the injured side (15.8%; P < 0.05). At 14 days, back PPT remained lower but similar side to side. At 3 days, paw PPT increased 34.6% in the contralateral rear limb following treatment (P < .01). Grip strength did not vary significantly. Gait coupling patterns improved significantly (P < .05). Circulating mesenchymal stem cell levels altered significantly postinjury but not with treatment. Neuropeptide Y plasma levels increased significantly at 3 days, 2h post-IASTM (53.2%) (P < .05). Interleukin-6 and tumor necrosis factor-alpha did not vary significantly. At 14 days, regulated on activation, normal T cell expressed and secreted decreased significantly <30-minute post-IASTM (96.1%, P < .002), while IL-10 trended upward at 2h (53.1%; P = .86).

CONCLUSIONS

LBP increased pain sensitivity and diminished function. IASTM treatment increased pain sensitization acutely in the back but significantly reduced pain sensitivity in the contralateral rear paw. Findings suggest IASTM may positively influence pain modulation and inflammation while improving gait patterns. Soft tissue manipulation may be beneficial as a conservative treatment option for LBP.

Evaluation of Potential Application of Wharton's Jelly-Derived Human Mesenchymal Stromal Cells and its Conditioned Media for Dermal Regeneration using Rat Wound Healing Model

Mesenchymal stromal cells and the derived conditioned media represent an area of tremendous medical interest and, among other clinical applications, are currently being extensively explored for wound healing. The aim of this study was to comparatively evaluate the wound healing potential of xeno-free human umbilical cord-derived mesenchymal stromal cells (MSCs) and the conditioned media (CM) in a full-thickness excision wound model in rats. The evaluation parameters included rate of wound healing, serum cytokine analyses, collagen content, histopathology, and hyperspectral imaging as an independent qualitative and quantitative tool. Both the cell-based and cell-free approaches scored better in lower inflammation, as evidenced in lower IL-10 and stable IL-6 levels, and improved rate of wound healing (p < 0.0001). More importantly, no adverse reaction or rejection was observed although human MSCs and CM were used in a xenogeneic model. The presence of hFGF, hHGF, hGCSF, hIL-1Ra, hVEGF, and hIL-6 in the secretome may elucidate the regenerative potential of the xeno-free cell-based and cell-free approaches which have translational value for advanced wound care. The results revealed the therapeutic potential of both the cell-based and cell-free approaches for wound healing.

The Use of Umbilical Cord-derived Mesenchymal Stem Cells Seeded Fibrin Matrix in the Treatment of Stage IV Acute Graft-Versus-Host Disease Skin Lesions in Pediatric Hematopoietic Stem Cell Transplant Patients

Mesenchymal stem cells (MSCs) have been used systemically or locally in many chronic and nonhealing skin lesions in recent years. In this study, umbilical cord-derived MSCs (UC-MSCs)-seeded fibrin matrix was used as a wound dressing in pediatric patients with stage 4 acute graft-versus-host disease (aGVHD)-induced desquamated skin lesions. This is the first study in which the UC-MSCs-seeded fibrin matrix was used as a wound dressing in aGVHD. A total of 14 times the MSCs-seeded fibrin matrix were applied to 9 patients as a wound dressing. On the seventh day, epithelialization and clinical response were evaluated. According to the size of the skin defect min: 1, max: 6 pieces were applied at a time. After 48 to 72 hours, it was observed that all of the MSCs-seeded fibrin matrixes adhered to the skin and the crustation started in 6 (43%) applications, whereas liquefaction was detected under all of them in 7 (50%) applications. Complete response was obtained in 6 applications (43%), partial response in 1 (7%), and no response in 7 applications (50%). This study showed that the MSCs-seeded fibrin matrix can be used effectively and safely in the matrix in the local treatment of aGVHD-induced skin wounds in pediatric patients.

Erythropoetin can partially restore cigarette smoke induced effects on Adipose derived Stem Cells

INTRODUCTION

Adipose derived Stem Cells (ASCs) have been proven to play a key role in tissue regeneration. However, exposure to large amounts of cigarette smoke can drastically diminish their function. Erythropoetin (EPO), can modulate cellular response to injury. Therefore, we investigated the ability of EPO to restore the regenerative function and differentiation capacity of ASCs.

MATERIAL AND METHODS

Human ASCs were isolated from abdominoplasty samples using standard isolation procedures. Cell identity was established by means of Fluorescence Activated Cell Scanning. Subsequently, isolated ASCs were cultivated with cigarette smoke extract both with and without EPO. Parameters investigated included cellular metabolic activity, adipogenic and osteogenic differentiation capacity, and in vitro wound closure capacity. For further enhancing wound closure, EPO was combined with Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) or Stromal Derived Factor-1 alpha (SDF-1 a).

RESULTS

Cigarette smoke reduces adipogenic differentiation, the osteogenic differentiation capacity as well as the in vitro wound healing ability of human derived ASCs. EPO did not change metabolic activity of ASCs significantly. The addition of EPO could partially restore their function. The combination of EPO with GM-CSF or SDF-1 did not result in a synergistic effect regarding wound healing ability.

CONCLUSION

Exposure to cigarette smoke significantly reduced the regenerative potential of ASCs. Treatment of ASCs exposed to cigarette smoke with EPO has the potential to partially restore their function.

Use of Cryopreserved Human Umbilical Cord and Amniotic Membrane Allograft and Portable Negative Pressure Therapy in Dehisced Giant Omphalocele Repair: A Case Study

BACKGROUND

A giant omphalocele is a rare congenital abdominal wall defect that measures more than 6 to 8 cm in any dimension. The child's abdominal visceral contents as well as the liver which are both covered by the amniotic sac protrude outside the abdomen through the umbilicus. Consequently, closing this defect is extremely challenging due to the risk for wound dehiscence.

CASE

Baby C, a 1-year-old male infant, developed a dehisced abdominal wound after secondary repair of a giant omphalocele. Escharification of the amniotic sac was achieved with silver products, followed by intra-abdominal tissue expansion and skin closure. A conservative approach was undertaken with the use of cryopreserved human umbilical cord and amniotic membrane allograft in conjunction with portable negative pressure therapy.

CONCLUSIONS

To the best of our knowledge, this is the first case study to evaluate the effect of cryopreserved human umbilical cord and amniotic membrane allograft in a dehisced neonatal abdominal wound due to a giant omphalocele or, in fact, neonatal wounds in general. Our experience with this case suggests that cryopreserved human umbilical cord and amniotic membrane allograft may create a superior healing trajectory and regeneration, avoidance of surgical intervention, and an early hospital discharge. Wound-supporting properties of amniotic allograft, in addition to lack of immunologic reactivity, offer an attractive option for a variety of pediatric and neonatal wounds.

Anti-Inflammatory Effects of Magnetically Targeted Mesenchymal Stem Cells on Laser-Induced Skin Injuries in Rats

Introduction

Mesenchymal stem cells (MSCs) are a promising resource for tissue regeneration and repair. However, their clinical application is hindered by technical limitations related to MSC enrichment at the target sites.

Methods

MSCs were labeled with magnetic Fe₃O₄ nanoparticles (NPs). We analyzed the effects of NP on cell proliferation, stem cell characteristics, and cytokine secretion. Furthermore, we induced NP-labeled MSC migration with an external magnetic field toward laser-induced skin wounds in rats and evaluated the associated anti-inflammatory effects.

Results

Fe₃O₄ NP application did not adversely affect MSC characteristics. Moreover, Fe₃O₄ NP-labeled MSCs presented increased anti-inflammatory cytokine and chemokine production compared with unlabeled MSCs. Furthermore, MSCs accumulated at the injury site and magnetic targeting promoted NP-labeled MSC migration toward burn injury sites in vivo. On day 7 following MSC injection, reduced inflammation and promoted angiogenesis were observed in the magnetically targeted MSC group. In addition, anti-inflammatory factors were upregulated, whereas pro-inflammatory factors were downregulated within the magnetically targeted MSC group compared with those in the PBS group.

Conclusion

This study demonstrates that magnetically targeted MSCs contribute to cell migration to the site of skin injury, improve anti-inflammatory effects and enhance angiogenesis compared with MSC injection alone. Therefore, magnetically targeted MSC therapy may be an effective treatment approach for epithelial tissue injuries.

Role of stem cell therapies in treating chronic wounds: A systematic review

BACKGROUND

The impairment of cutaneous wound healing results in chronic, non-healing wounds that are caused by altered wound environment oxygenation, tissue injury, and permissive microbial growth. Current modalities for the treatment of these wounds inadequately address the complex changes involved in chronic wound pathogenesis. Consequently, stem cell therapies have emerged as a potential therapeutic modality to promote cutaneous regeneration through trophic and paracrine activity.

AIM

To investigate current literature regarding use of stem cell therapies for the clinical treatment of chronic, non-healing wounds.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus were queried with combinations of the search terms “mesenchymal stem cells,” “adult stem cells,” “embryonic stem cells,” “erythroid precursor cells,” “stem cell therapies,” and “chronic wounds” in order to find relevant articles published between the years of 2000 and 2019 to review a 20-year experience. Reference lists from the articles were reviewed to identify additional pertinent articles. Retrieved manuscripts (reviews, case reports/series, retrospective/prospective studies, and clinical trials) were evaluated by the authors for their depiction of clinical stem cell therapy use. Data were extracted from the articles using a standardized collection tool.

RESULTS

A total of 43 articles describing the use of stem cell therapies for the treatment of chronic wounds were included in this review. While stem cell therapies have been explored in in vitro and in vivo applications in the past, recent efforts are geared towards assessing their clinical role. A review of the literature revealed that adipose-derived stem cells, bone marrow-derived stem cells, bone marrow-derived mononuclear cells, epidermally-derived mesenchymal stem cells, fibroblast stem cells, keratinocyte stem cells, placental mesenchymal stem cells, and umbilical cord mesenchymal stem cells have all been employed in the treatment of chronic wounds of various etiologies. Most recently, embryonic stem cells have emerged as a novel stem cell therapy with the capacity for multifaceted germ cell layer differentiation. With the capacity for self-renewal and differentiation, stem cells can enrich existing cell populations in chronic wounds in order to overcome barriers impeding the progression of wound healing. Further, stem cell therapies can be utilized to augment cell engraftment, signaling and activity, and resultant patient outcomes.

CONCLUSION

Assessing observed clinical outcomes, potential for stem cell use, and relevant therapeutic challenges allows wound care stakeholders to make informed decisions regarding optimal treatment approaches for their patients’ chronic wounds.

Cellular senescence is a promising target for chronic wounds: a comprehensive review

Chronic wounds include, but are not limited to, radiation ulcers, pressure ulcers, vascular ulcers and diabetic foot ulcers. These chronic wounds can persist for years without healing and severe ulcers may lead to amputation. Unfortunately, the underlying pathologies of refractory chronic wounds are not fully characterized, and new treatments are urgently needed. Recently, increasing evidence has indicated that cell senescence plays an important role in the development of chronic wounds, and preventing cell senescence or removing senescent cells holds promise as a new therapeutic strategy. In this review, we aim to probe these latest findings to promote the understanding of cellular senescence in the pathological process and potential management of chronic wounds.

Antitumor effect of cell therapy with mesenchymal stem cells on murine melanoma B16-F10

In this study, the antitumor and immunomodulatory effects of mesenchymal stem cells (MSC) obtained from bone marrow in the treatment of dorsal melanoma B16-F10. The MSC cells were obtained from the bone marrow of isogenic C57BL/6J mice, characterized and inoculated by two routes, intratumor (it) and intravenous (iv). The hematological profile, expression markers and receptors, phases of the cell cycle and mitochondrial electrical potential were evaluated by flow cytometry. The dorsal tumor mass showed a significant reduction after treatment by the two routes of administration with a significant effect by the intravenous route. MSC showed immunomodulatory potential and did not induce an increase in the markers involved in tumor control and progression. The number of cells in the sub-G1 phase increased significantly after treatments compared to the control group. The percentage of cells in phases G0/G1, S and G2/M decreased, with only the group (it) showing a significant reduction. The intratumor group showed a significant decrease in the G2/M phase. Treatment with MSC provided a significant decrease in the percentage of metabolically active tumor cells, demonstrating its intrinsic effect in the control of cell proliferation. Regarding the mechanism of cell death, MSCs modulated the expression of proteins involved in the regulation of the cell cycle, angiogenesis receptors and pro-apoptotic proteins by intrinsic and extrinsic routes. Therefore, the use of undifferentiated MSC, administered intratumor and intravenous is possibly a promising treatment for melanoma.

Growth and Osteogenic Differentiation of Discarded Gingiva-Derived Mesenchymal Stem Cells on a Commercial Scaffold

BACKGROUND

In periodontal patients with jawbone resorption, the autologous bone graft is considered a "gold standard" procedure for the placing of dental prosthesis; however, this procedure is a costly intervention and poses the risk of clinical complications. Thanks to the use of adult mesenchymal stem cells, smart biomaterials, and active biomolecules, regenerative medicine and bone tissue engineering represent a valid alternative to the traditional procedures.

AIMS

In the past, mesenchymal stem cells isolated from periodontally compromised gingiva were considered a biological waste and discarded during surgical procedures. This study aims to test the osteoconductive activity of FISIOGRAFT Bone Granular® and Matriderm® collagen scaffolds on mesenchymal stem cells isolated from periodontally compromised gingiva as a low-cost and painless strategy of autologous bone tissue regeneration.

MATERIALS AND METHODS

We isolated human mesenchymal stem cells from 22 healthy and 26 periodontally compromised gingival biopsy tissues and confirmed the stem cell phenotype by doubling time assay, colony-forming unit assay, and expression of surface and nuclear mesenchymal stem cell markers, respectively by cytofluorimetry and real-time quantitative PCR. Healthy and periodontally compromised gingival mesenchymal stem cells were seeded on FISIOGRAFT Bone Granular® and Matriderm® scaffolds, and in vitro cell viability and bone differentiation were then evaluated.

RESULTS

Even though preliminary, the results demonstrate that FISIOGRAFT Bone Granular® is not suitable for in vitro growth and osteogenic differentiation of healthy and periodontally compromised mesenchymal stem cells, which, instead, are able to grow, homogeneously distribute, and bone differentiate in the Matriderm® collagen scaffold.

CONCLUSION

Matriderm® represents a biocompatible scaffold able to support the in vitro cell growth and osteodifferentiation ability of gingival mesenchymal stem cells isolated from waste gingiva, and could be employed to develop low-cost and painless strategy of autologous bone tissue regeneration.

Comprehensive Proteomic Profiling of Pressure Ulcers in Patients with Spinal Cord Injury Identifies a Specific Protein Pattern of Pathology

Objective: Severe pressure ulcers (PUs) do not respond to conservative wound therapy and need surgical repair. To better understand the pathogenesis and to advance on new therapeutic options, we focused on the proteomic analysis of PU, which offers substantial opportunities to identify significant changes in protein abundance during the course of PU formation in an unbiased manner. Approach: To better define the protein pattern of this pathology, we performed a proteomic approach in which we compare severe PU tissue from spinal cord injury (SCI) patients with control tissue from the same patients. Results: We found 76 proteins with difference in abundance. Of these, 10 proteins were verified as proteins that define the pathology: antithrombin-III, alpha-1-antitrypsin, kininogen-1, alpha-2-macroglobulin, fibronectin, apolipoprotein A-I, collagen alpha-1 (XII) chain, haptoglobin, apolipoprotein B-100, and complement factor B. Innovation: This is the first study to analyze differential abundance protein of PU tissue from SCI patients using high-throughput protein identification and quantification by tandem mass tags followed by liquid chromatography tandem mass spectrometry. Conclusion: Differential abundance proteins are mainly involved in tissue regeneration. These proteins might be considered as future therapeutic options to enhance the physiological response and permit cellular repair of damaged tissue.

Efficacy of topical epigallocatechin gallate (EGCG) 1% on the healing of chronic plantar ulcers in leprosy

BACKGROUND

Chronic plantar ulcers in leprosy (CPUL) occur in areas that have a sensory and an autonomic nerve impairment where the wound healing takes longer. Framycetin gauze dressing (FGD) is best used in the wound healing process during the inflammatory phase because it contains antibiotics. Epigallocatechin gallate (EGCG) is the highest component in the extract of green tea that can accelerate blood vessel formation, has an anti-inflammatory effect, and reepithelialization.

OBJECTIVE

To investigate the effect of topical EGCG 1% on the healing of CPUL.

MATERIALS AND METHODS

An analytical experimental approach comparing the topical EGCG 1% and FGD applied every 3 days up to 8 weeks on the healing of CPUL. Size of the ulcers, side effects and possible complications from both approaches were monitored weekly.

RESULTS

Ulcer healing in the EGCG group was significantly better than the FGD group with significant clinical and statistical differences (p < .032). There were no side effects in both the study groups. Complications, such as an increase in the size of the ulcer, were noted in one subject in the control group. This may have been caused by FGD and claw foot condition.

CONCLUSIONS

EGCG 1% is more effective than FGD in accelerating the healing process of CPUL.

In situ miRNA delivery from a hydrogel promotes osteogenesis of encapsulated mesenchymal stromal cells

Hydrogels are attractive candidates for use in tissue-engineering and the encapsulation and subsequent differentiation of mesenchymal stem/stromal cells (MSCs) is a strategy that holds great promise for the repair and regeneration of bone and cartilage. However, MSCs are well-known for their sensitivity to mechanical cues, particularly substrate stiffness, and so the inherent softness of hydrogels is poorly matched to the mechanical cues that drive efficient osteogenesis. One approach to overcome this limitation is to harness mechanotransductive signalling pathways and override the signals cells receive from their environment. Previous reports demonstrate that mechanosensitive miRNAs, miR-100-5p and miR-143-3p can enhance MSC osteogenesis, using a complex multi-step procedure to transfect, encapsulate and differentiate the cells. In this study, we develop and characterise a facile system for in situ transfection of MSCs encapsulated within a light-crosslinkable gelatin-PEG hydrogel. Comparing the influence of different transfection agents and hydrogel compositions, we show that particle size, charge, and hydrogel mechanical properties all influence the diffusion of embedded transfection agent complexes. By incorporating both MSCs and transfection agents into the hydrogels we demonstrate successful in situ transfection of encapsulated MSCs. Comparing the efficacy of pre- and in situ transfection of miR-100-5p/miR-143-3p on the osteogenic capacity of hydrogel-encapsulated MSCs, our data demonstrates superior mineralisation and osteogenic gene expression following in situ transfections. Overall, we demonstrate a simple, one-pot system for in situ transfection of miRNAs to enhance MSC osteogenic potential and thus demonstrates significant promise to improve the efficiency of MSC differentiation in hydrogels for bone tissue-engineering applications. STATEMENT OF SIGNIFICANCE: Mesenchymal stromal cells (MSCs) are sensitive to cues from their surrounding microenvironment. Osteogenesis is enhanced in MSCs grown on stiffer substrates, but this is limited when using hydrogels for bone tissue-engineering. Modulating pro-osteogenic genes with mechanosensitive microRNAs (miRNAs) represents a potential tool to overcome this challenge. Here we report a hydrogel platform to deliver miRNAs to encapsulated MSCs. We characterise effects of hydrogel composition and transfection agent type on their mobility and transfection efficiency, demonstrating successful in situ transfection of MSCs and showing that miRNAs can significantly enhance osteogenic mineral deposition and marker gene expression. This system was simpler and more effective than conventional 2D transfection prior to encapsulation and therefore holds promise to improve MSC differentiation in bone tissue-engineering.

N-Acetyl-cysteine and Mechanisms Involved in Resolution of Chronic Wound Biofilm

Chronic wounds are a major global health problem with the presence of biofilm significantly contributing to wound chronicity. Current treatments are ineffective in resolving biofilm and simultaneously killing the bacteria; therefore, effective biofilm-resolving drugs are needed. We have previously shown that, together with α-tocopherol, N-acetyl-cysteine (NAC) significantly improves the healing of biofilm-containing chronic wounds, in a diabetic mouse model we developed, by causing disappearance of the bacteria and breakdown of the extracellular polymeric substance (EPS). We hypothesize that NAC creates a microenvironment that affects bacterial survival and EPS integrity. To test this hypothesis, we developed an in vitro biofilm system using microbiome taken directly from diabetic mouse chronic wounds. For these studies, we chose mice in which chronic wound microbiome was rich in Pseudomonas aeruginosa (97%). We show that NAC at concentrations with pH < pKa causes bacterial cell death and breakdown of EPS. When used before biofilm is formed, NAC leads to bacterial cell death whereas treatment after the biofilm is established NAC causes biofilm dismantling accompanied by bacterial cell death. Mechanistically, we show that NAC can penetrate the bacterial membrane, increase oxidative stress, and halt protein synthesis. We also show that low pH is important for the actions of NAC and that bacterial death occurs independently of the presence of biofilm. In addition, we show that both the acetyl and carboxylic groups play key roles in NAC functions. The results presented here provide insight into the mechanisms by which NAC dismantles biofilm and how it could be used to treat chronic wounds after debridement (NAC applied at the start of culture) or without debridement (NAC applied when biofilm is already formed). This approach can be taken to develop biofilm from microbiome taken directly from human chronic wounds to test molecules that could be effective for the treatment of specific biofilm compositions.

Mechanoresponse of stem cells for vascular repair

Stem cells have shown great potential in vascular repair. Numerous evidence indicates that mechanical forces such as shear stress and cyclic strain can regulate the adhesion, proliferation, migration, and differentiation of stem cells via serious signaling pathways. The enrichment and differentiation of stem cells play an important role in the angiogenesis and maintenance of vascular homeostasis. In normal tissues, blood flow directly affects the microenvironment of vascular endothelial cells (ECs); in pathological status, the abnormal interactions between blood flow and vessels contribute to the injury of vessels. Next, the altered mechanical forces are transduced into cells by mechanosensors to trigger the reformation of vessels. This process occurs when signaling pathways related to EC differentiation are initiated. Hence, a deep understanding of the responses of stem cells to mechanical stresses and the underlying mechanisms involved in this process is essential for clinical translation. In this the review, we provide an overview of the role of stem cells in vascular repair, outline the performance of stem cells under the mechanical stress stimulation, and describe the related signaling pathways.

Advanced drug delivery systems and artificial skin grafts for skin wound healing

Cutaneous injuries, especially chronic wounds, burns, and skin wound infection, require painstakingly long-term treatment with an immense financial burden to healthcare systems worldwide. However, clinical management of chronic wounds remains unsatisfactory in many cases. Various strategies including growth factor and gene delivery as well as cell therapy have been used to enhance the healing of non-healing wounds. Drug delivery systems across the nano, micro, and macroscales can extend half-life, improve bioavailability, optimize pharmacokinetics, and decrease dosing frequency of drugs and genes. Replacement of the damaged skin tissue with substitutes comprising cell-laden scaffold can also restore the barrier and regulatory functions of skin at the wound site. This review covers comprehensively the advanced treatment strategies to improve the quality of wound healing.

The role of microRNAs in the healing of diabetic ulcers

MicroRNAs (miRNAs) are small protected molecules with a length of 18 to 25 nucleotides. Many studies have recently been conducted on miRNAs, illustrating their role in regulating many biological, physiological, and pathological activities, such as maintaining cellular signalling and regulating cellular pathways. The main role of miRNAs is to regulate the expression of genes after translation, which can lead to the destruction or suppression of translation by binding to mRNAs. As any change in the regulation of miRNAs is associated with several physiological abnormalities, such as type 2 diabetes and its complications, these molecules can be used for therapeutic purposes or as biomarkers for the diagnosis of diseases such as diabetes and its complications. In this review article, we will discuss important findings about the miRNAs and the role of these molecules in different phases of the wound-healing process of chronic wounds, especially diabetic ulcer.

Substance P accelerates wound repair by promoting neovascularization and preventing inflammation in an ischemia mouse model

AIMS

Arterial insufficiency ulcers are frequent complications of peripheral artery disease and infection or long-term neglect of the ulcer can eventually lead to amputation of the affected body part. An ischemic environment, caused by interrupted blood flow, affects the supply of nutrients and elongates the inflammation period, inducing tissue degeneration. Thus, the modulation of neovascularization and inflammation could be an ideal therapeutic strategy for ischemic wound healing. This study aimed to elucidate whether systemically administered substance P (SP) could promote ischemic wound repair in mice by restoring blood perfusion and suppressing inflammation.

MAIN METHODS

The effects of SP were assessed by analyzing wound size, blood flow, epidermal and dermal layer regeneration, vessel formation, and the inflammatory cytokine profiles in a hind-limb ischemia non-clinical mouse model.

KEY FINDINGS

SP-treated mice exhibited dramatically rapid wound healing and restoration of blood flow within the ischemic zone, compared with saline-treated mice. Notably, SP-treated mice showed enhanced pericyte-covered vasculature compared to saline-treated mice. Moreover, anti-inflammatory effects were detected in mice in the SP-treated group, including suppression of inflammation-mediated spleen enlargement, reduction of tumor necrosis factor-alpha, and promotion of circulatory interleukin-10 levels.

SIGNIFICANCE

These results suggest that SP could be a possible therapeutic candidate for patients with peripheral artery disease, including those with ischemic ulcers.

The effects of graphene and mesenchymal stem cells in cutaneous wound healing and their putative action mechanism

This study provides a review of the therapeutic potential of graphene dressing scaffolds and mesenchymal stem cells (MSCs) and their synergistic effects with respect to cutaneous wound healing. This study also considers their putative action mechanism based on the antibacterial, immunomodulating, angiogenic, matrix remodeling effects of materials belonging to the graphene family and MSCs during the wound healing process. In addition, this study discusses the cytocompatibility of graphene, its uses as a platform for skin substitutes, the properties it possesses with respect to providing protection against microbial invasion as well as strategies aimed at minimizing the chance of the occurrence of sepsis. MSCs are capable of secreting several factors that exert a therapeutic impact on reparative processes and tissue regeneration. In light of experiments conducted to date, graphene combined with MSCs appears to have the potential to enhance both the wound healing process and infection control at the injury site.

Wound healing complications in oncological patients: perspectives for cellular therapy

Various types of cancer are nowadays a serious medical and social problem and a great challenge for modern medicine. The majority of anticancer therapy is based on traditional chemotherapy and radiotherapy. Both of these highly non-specific types of treatment have a number of serious side effects including wound healing complications. Radiotherapy and chemotherapy mostly affect rapidly dividing skin cells (e.g. keratinocytes), as well as fibroblasts, melanocytes, endothelial and immune cells. Currently, there are many strategies to improve wound healing in oncological patients, including various types of dressings, biomaterials, growth factors, and cell therapies.

Autologous nanofat transplantation accelerates foot wound healing in diabetic rats

Aim: This study explored the effects of local transplantation of autologous nanofat in the treatment of rats with diabetic foot wounds. Materials & methods: Nanofat was transplanted into the left foot wound of diabetic rats. Phosphate-buffered saline injection in the right served as control. We measured wound size, the extent of epithelization, microvessel density and the expression levels of cytokines at six different time-points postoperation. Results: Compared with the control feet, nanofat-treated feet had significantly smaller wound areas at 7 and 9 days after grafting and showed better re-epithelialization, a greater number of microvessels and higher levels of angiogenic factor expression. Conclusion: This research shows that autologous nanofat transplantation can promote diabetic foot wound healing in rats.

Characterization of the Kinetics and Mechanism of Degradation of Human Mesenchymal Stem Cell-Laden Poly(ethylene glycol) Hydrogels

Human mesenchymal stem cells (hMSCs) are motile cells that migrate from their native niche to wounded sites where they regulate inflammation during healing. New materials are being developed as hMSC delivery platforms to enhance wound healing. To act as an effective wound healing material, the hydrogel must degrade at the same rate as tissue regeneration, while maintaining a high cell viability. This work determines the kinetics and mechanism of cell-mediated degradation in hMSC-laden poly(ethylene glycol) (PEG) hydrogels. We use a well-established hydrogel scaffold that is composed of a backbone of four-arm star PEG functionalized with norbornene that is cross-linked with a matrix metalloproteinase (MMP) degradable peptide. This peptide sequence is cleaved by cell-secreted MMPs, which allow hMSCs to actively degrade the hydrogel during motility. Three mechanisms of degradation are characterized: hydrolytic, noncellular enzymatic and cell-mediated degradation. We use bulk rheology to characterize hydrogel material properties and quantify degradation throughout the entire reaction. Hydrolysis and noncellular enzymatic degradation are first characterized in hydrogels without hMSCs, and follow first-order and Michaelis-Menten kinetics, respectively. A high cell viability is measured in hMSC-laden hydrogels, even after shearing on the rheometer. After confirming hMSC viability, bulk rheology characterizes cell-mediated degradation. When comparing cell-mediated degradation to noncellular degradation mechanisms, cell-mediated degradation is dominated by enzymatic degradation. This indicates hydrogels with hMSCs are degraded primarily due to cell-secreted MMPs and very little network structure is lost due to hydrolysis. Modeling cell-mediated degradation provides an estimate of the initial concentration of MMPs secreted by hMSCs. By changing the concentration of hMSCs, we determine the initial MMP concentration increases with increasing hMSC concentration. This work characterizes the rate and mechanism of scaffold degradation, giving new insight into the design of these materials as implantable scaffolds.

Regenerative potential of partially differentiated mesenchymal stromal cells in a mouse model of a full-thickness skin wound

Mesenchymal stromal cells (MSCs, known as mesenchymal stem cells) are considered to be a promising therapeutic tool for many diseases. But it is still unclear which cells are more efficient and safe for wound healing and tissue regeneration for clinical applications: undifferentiated, partially differentiated stem cells or differentiated cells. In this study, we modified MSCs with keratinocyte-conditioned medium (KCM) and examined MSCs, partially differentiated MSCs (PMSCs) and differentiated cell migration, accumulation in the wounded area as well as cell regenerative efficiency in a full-thickness skin wound model. In addition to that, the impact of intradermal and intravenous cell delivery methods of wound healing was evaluated. C57BL/6J mouse compact bone MSCs were treated with a KCM for 14 days. Flow cytometry analysis showed the appearance of keratinocyte surface markers which were absent in MSCs, whereas the specific markers for MSCs were lost. Cells were injected either intravenously or intradermally in C57BL/6J mice. Wound closure, cell migration and accumulation in the wounded area were further analysed. Wound healing was assessed by the rate of wound closure and by histological evaluation. Cells were monitored using optical imaging. We demonstrated that PMSCs showed morphology similar to keratinocyte cells, had enhanced migration and increased survival at the site of injury. PMSCs had a beneficial effect on wound healing and tissue regeneration. This effect was reinforced when these cells were injected intravenously. Due to their partial differentiation status, we assume that PMSCs can differentiate more rapidly into epidermal cell lineages thus causing faster and qualitatively improved wound healing.

Advancements in Regenerative Strategies Through the Continuum of Burn Care

Burns are caused by several mechanisms including flame, scald, chemical, electrical, and ionizing and non-ionizing radiation. Approximately half a million burn cases are registered annually, of which 40 thousand patients are hospitalized and receive definitive treatment. Burn care is very resource intensive as the treatment regimens and length of hospitalization are substantial. Burn wounds are classified based on depth as superficial (first degree), partial-thickness (second degree), or full-thickness (third degree), which determines the treatment necessary for successful healing. The goal of burn wound care is to fully restore the barrier function of the tissue as quickly as possible while minimizing infection, scarring, and contracture. The aim of this review is to highlight how tissue engineering and regenerative medicine strategies are being used to address the unique challenges of burn wound healing and define the current gaps in care for both partial- and full-thickness burn injuries. This review will present the current standard of care (SOC) and provide information on various treatment options that have been tested pre-clinically or are currently in clinical trials. Due to the complexity of burn wound healing compared to other skin injuries, burn specific treatment regimens must be developed. Recently, tissue engineering and regenerative medicine strategies have been developed to improve skin regeneration that can restore normal skin physiology and limit adverse outcomes, such as infection, delayed re-epithelialization, and scarring. Our emphasis will be centered on how current clinical and pre-clinical research of pharmacological agents, biomaterials, and cellular-based therapies can be applied throughout the continuum of burn care by targeting the stages of wound healing: hemostasis, inflammation, cell proliferation, and matrix remodeling.

Functional and histologic effects after implanting pluripotent stem cells in a murine model with sphincterotomy

INTRODUCTION AND AIMS

Fecal incontinence is a disabling condition with devastating consequences for the patients. Medical and surgical options are not very satisfactory, reason by which regenerative medicine has been considered in this field. In the present research, we analyzed functional and histologic effects after implanting pluripotent stem cells (PSCs) in a murine model with sphincterotomy.

MATERIALS AND METHODS

Female Wistar rats were subjected to sphincterotomy and divided into three groups. Group 1 (control group) was treated with 300μL of balanced saline solution and group 2 (late treatment) and group 3 (early treatment) received 50,000 PSCs resuspended in 300μL of balanced saline solution. All animals were evaluated through high-resolution anorectal manometry 24hours before and after sphincterotomy and every month for three months. Finally, the rats were euthanized and histopathologic sections from the anal canal were obtained.

RESULTS

All groups showed a decrease in resting anal pressure and squeeze anal pressure 24hours after sphincterotomy. At the third month, higher anal pressures in the groups treated with PSCs were detected. Regarding the histologic effects, the microscopic architecture was restored and there was a significant decrease in the inflammatory response in the groups treated with PSCs.

CONCLUSION

PSCs implantation improves anal tone, as well as histologic structure, presenting better regenerative results when implanted as early treatment.