Comparison of the histological morphology between normal skin and scar tissue

Elastic Nanofibrous Dressings with Mesenchymal Stem Cell-Recruiting and Protecting Characteristics for Promoting Diabetic Wound Healing

Diabetic wounds that do not heal for a long time challenge global healthcare. Mesenchymal stem cell (MSC) therapy has positive significance in promoting diabetic wound healing. However, traditional MSC therapy involves exogenous MSCs, which brings many limitations and unsatisfactory treatment. Moreover, the maintenance of MSC viability and function is difficult because of the high level of reactive oxygen species (ROS) in diabetic wounds. Therefore, we developed a nanofibrous dressing to recruit and protect endogenous MSCs while avoiding the inherent disadvantages of exogenous MSCs. Ceria nanoparticles capable of ROS scavenging are integrated into the nanofibrous dressings, together with Apt19S, a DNA aptamer with affinity and selectivity for MSCs. In addition, the homogenization and freeze-drying technology give the nanofibrous dressings good elasticity, which protects the wound from external pressure. Further experiments in diabetic mice show that the dressing has excellent endogenous MSC recruitment and anti-inflammatory properties, thereby synergistically promoting diabetic wound healing. This study is expected to explore an efficient method of stem cell therapy, providing a new way to construct high-performance wound dressings.

Dendrobium officinale Kinura et Migo glycoprotein promotes skin wound healing by regulating extracellular matrix secretion and fibroblast proliferation on the proliferation phase

Dendrobium officinale Kinura et Migo (DOKM) has a variety of medicinal applications; however, its ability to promote wound healing has not been previously reported. The purpose of this study is to investigate the proliferative phase of the wound-healing effect of DOKM glycoprotein (DOKMG) in rats and to elucidate its mechanism of action in vitro. In the present study, the ointment mixture containing DOKMG was applied to the dorsal skin wounds of the full-thickness skin excision rat model, and the results showed that the wound healing speed was faster in the proliferative phase than vaseline. Histological analysis demonstrates that DOKMG promoted the re-epithelialization of wound skin. Immunofluorescence staining and quantitative polymerase chain reaction assays revealed that DOKMG promotes the secretion of Fibronectin and inhibits the secretion of Collagen IV during the granulation tissue formation period, indicating that DOKMG could accelerate the formation of granulation tissue by precisely regulating extracellular matrix (ECM) secretion. In addition, we demonstrated that DOKMG enhanced the migration and proliferation of fibroblast (3T6 cell) in two-dimensional trauma by regulating the secretion of ECM, via a mechanism that may implicate the AKT and JAK/STAT pathways under the control of epidermal growth factor receptor (EGFR) signalling. In summary, we have demonstrated that DOKMG promotes wound healing during the proliferative phase. Therefore, we suggest that DOKMG may have a potential therapeutic application for the treatment and management of cutaneous wounds.

Construction of a dual-component hydrogel matrix for 3D biomimetic skin based on photo-crosslinked chondroitin sulfate/collagen

The main challenge in the field of 3D biomimetic skin is to search for a suitable hydrogel matrix with good biocompatibility, appropriate mechanical property and inner porosity that can support the adhesion and proliferation of skin cells. In this study, photocurable chondroitin sulfate methacrylate (CSMA) and collagen methacrylate (CoLMA) synthesized from chondroitin sulfate (CS) and type I collagen I (CoL) in the dermal matrix were used to construct a photo-crosslinked dual-component CSMA-CoLMA hydrogel matrix. Due to the toughening effect of the dual-component, the CSMA-CoLMA hydrogel improved the intrinsic brittleness of the single-component CSMA hydrogel, presented good mechanical tunability. The average storage and elasticity modulus could reach 3.3 KPa and 30.3 KPa, respectively, which were close to those of natural skin. The CSMA-CoLMA hydrogel with a ratio of 8/6 showed suitable porous structure and good biocompatibility, supporting the adhesion and proliferation of skin cells. Furthermore, the expression of characteristic marker proteins was detected in the epidermal and dermal bi-layered models constructed with the hydrogel containing keratinocytes and fibroblasts. These results suggest that the dual-component CSMA-CoLMA hydrogel has promising potential as a matrix to construct 3D biomimetic skin.

Anagen hair follicles transplanted into mature human scars remodel fibrotic tissue

Despite the substantial impact of skin scarring on patients and the healthcare system, there is a lack of strategies to prevent scar formation, let alone methods to remodel mature scars. Here, we took a unique approach inspired by how healthy hairbearing skin undergoes physiological remodelling during the regular cycling of hair follicles. In this pilot clinical study, we tested if hair follicles transplanted into human scars can facilitate tissue regeneration and actively remodel fibrotic tissue, similar to how they remodel the healthy skin. We collected full-thickness skin biopsies and compared the morphology and transcriptional signature of fibrotic tissue before and after transplantation. We found that hair follicle tranplantation induced an increase in the epidermal thickness, interdigitation of the epidermal-dermal junction, dermal cell density, and blood vessel density. Remodelling of collagen type I fibres reduced the total collagen fraction, the proportion of thick fibres, and their alignment. Consistent with these morphological changes, we found a shift in the cytokine milieu of scars with a long-lasting inhibition of pro-fibrotic factors TGFβ1, IL13, and IL-6. Our results show that anagen hair follicles can attenuate the fibrotic phenotype, providing new insights for developing regenerative approaches to remodel mature scars.

Defining invasion in breast cancer: the role of basement membrane

Basement membrane (BM) is an amorphous, sheet-like structure separating the epithelium from the stroma. BM is characterised by a complex structure comprising collagenous and non-collagenous proteoglycans and glycoproteins. In the breast, the thickness, density and composition of the BM around the ductal lobular system vary during differing development stages. In pathological conditions, the BM provides a physical barrier that separates proliferating intraductal epithelial cells from the surrounding stroma, and its absence or breach in malignant lesions is a hallmark of invasion and metastases. Currently, diagnostic services often use special stains and immunohistochemistry (IHC) to identify the BM in order to distinguish in situ from invasive lesions. However, distinguishing BM on stained sections, and differentiating the native BM from the reactive capsule or BM-like material surrounding some invasive malignant breast tumours is challenging. Although diagnostic use of the BM is being replaced by myoepithelial cell IHC markers, BM is considered by many to be a useful marker to distinguish in situ from invasive lesions in ambiguous cases. In this review, the structure, function and biological and clinical significance of the BM are discussed in relation to the various breast lesions with emphasis on how to distinguish the native BM from alternative pathological tissue mimicking its histology.

Automated Structural Analysis and Quantitative Characterization of Scar Tissue Using Machine Learning

An analysis of scar tissue is necessary to understand the pathological tissue conditions during or after the wound healing process. Hematoxylin and eosin (HE) staining has conventionally been applied to understand the morphology of scar tissue. However, the scar lesions cannot be analyzed from a whole slide image. The current study aimed to develop a method for the rapid and automatic characterization of scar lesions in HE-stained scar tissues using a supervised and unsupervised learning algorithm. The supervised learning used a Mask region-based convolutional neural network (RCNN) to train a pattern from a data representation using MMDetection tools. The K-means algorithm characterized the HE-stained tissue and extracted the main features, such as the collagen density and directional variance of the collagen. The Mask RCNN model effectively predicted scar images using various backbone networks (e.g., ResNet50, ResNet101, ResNeSt50, and ResNeSt101) with high accuracy. The K-means clustering method successfully characterized the HE-stained tissue by separating the main features in terms of the collagen fiber and dermal mature components, namely, the glands, hair follicles, and nuclei. A quantitative analysis of the scar tissue in terms of the collagen density and directional variance of the collagen confirmed 50% differences between the normal and scar tissues. The proposed methods were utilized to characterize the pathological features of scar tissue for an objective histological analysis. The trained model is time-efficient when used for detection in place of a manual analysis. Machine learning-assisted analysis is expected to aid in understanding scar conditions, and to help establish an optimal treatment plan.

Increased temperature at the healed area detected by thermography predicts recurrent pressure ulcers

Preventing recurrent pressure ulcers is an important challenge in healthcare. One of the reasons for the high rate of recurrent pressure ulcers is the lack of assessment methods for their early detection. Therefore, this study aimed to determine the thermographic characteristics of the healed area and to consider the predictive validity of thermographic images for recurrent pressure ulcers within a 2-week period. This observational study was conducted at a long-term care facility in Japan between July 2017 and February 2019 among patients whose pressure ulcers had healed. Thermographic images of the healed area were recorded once a week until recurrence or until the end of the study. We enrolled 30 participants, among whom 8 developed recurrent pressure ulcers. The generalised estimation equation revealed that the thermographic finding of increased temperature at the healed area compared to that of the surrounding skin was significantly associated with recurrent pressure ulcers (odds ratio: 101.13, 95% confidence interval: 3.60-2840.77, p = .007); the sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio for recurrent pressure ulcers within 2 weeks were 0.80, 0.94, 0.62, 0.97, 12.9 and 0.2, respectively. Our thermographic findings revealed that the temperature of the healed area was higher than that of the surrounding skin; this could be a useful predictor of pressure ulcer recurrence within 2 weeks, even in the absence of macroscopic changes.

Unlocking mammalian regeneration through hypoxia inducible factor one alpha signaling

Historically, the field of regenerative medicine has aimed to heal damaged tissue through the use of biomaterials scaffolds or delivery of foreign progenitor cells. Despite 30 years of research, however, translation and commercialization of these techniques has been limited. To enable mammalian regeneration, a more practical approach may instead be to develop therapies that evoke endogenous processes reminiscent of those seen in innate regenerators. Recently, investigations into tadpole tail regrowth, zebrafish limb restoration, and the super-healing Murphy Roths Large (MRL) mouse strain, have identified ancient oxygen-sensing pathways as a possible target to achieve this goal. Specifically, upregulation of the transcription factor, hypoxia-inducible factor one alpha (HIF-1α) has been shown to modulate cell metabolism and plasticity, as well as inflammation and tissue remodeling, possibly priming injuries for regeneration. Since HIF-1α signaling is conserved across species, environmental or pharmacological manipulation of oxygen-dependent pathways may elicit a regenerative response in non-healing mammals. In this review, we will explore the emerging role of HIF-1α in mammalian healing and regeneration, as well as attempts to modulate protein stability through hyperbaric oxygen treatment, intermittent hypoxia therapy, and pharmacological targeting. We believe that these therapies could breathe new life into the field of regenerative medicine.

Novel ECM Patch Combines Poly(vinyl alcohol), Human Fibroblast-Derived Matrix, and Mesenchymal Stem Cells for Advanced Wound Healing

Decellularized extracellular matrix (ECM)-based scaffold has been a very useful resource for effective tissue regeneration. In this study, we report a novel ECM patch that physically combines human fibroblast-derived matrix (hFDM) and poly(vinyl alcohol) (PVA) hydrogel. hFDM was obtained after decellularization of in vitro cultured human fibroblasts. We investigated the basic characteristics of hFDM alone using immunofluorescence (fibronectin, collagen type I) and angiogenesis-related factor analysis. Successful incorporation of hFDM with PVA produced an hFDM/PVA patch, which showed excellent cytocompatibility with human mesenchymal stem cells (hMSCs), as assessed via cell adhesion, viability, and proliferation. Moreover, in vitro scratch assay using human dermal fibroblasts showed a significant improvement of cell migration when treated with the paracrine factors originated from the hMSC-incorporated hFDM. To evaluate the therapeutic effect on wound healing, hMSCs were seeded on the hFDM/PVA patch and they were then transplanted into a mouse full-thickness wound model. Among four experimental groups (control, PVA, hFDM/PVA, hMSC/hFDM/PVA), we found that hMSC/hFDM/PVA patch accelerated the wound closure with time. More notably, histology and immunofluorescence demonstrated that compared to the other interventions tested, hMSC/hFDM/PVA patch could lead to significantly advanced tissue regeneration, as confirmed via nearly normal epidermis thickness, skin adnexa regeneration (hair follicle), mature collagen deposition, and neovascularization. Additionally, cell tracking of prelabeled hMSCs suggests the in vivo retention of transplanted cells in the wound region after the transplantation of hMSC/hFDM/PVA patch. Taken together, our engineered ECM patch supports a strong regenerative potential toward advanced wound healing.

Development of recurrent pressure ulcers, risk factors in older patients: a prospective observational study

Objective:

Prevention of recurrent pressure ulcers (PU) is one of the most important challenges in wound care, furthermore, the risk factors for recurrent PUs are still not fully understood. This study aimed to explore the risk factors for recurrent PU development within two weeks, including biophysical skin properties, pro-inflammatory cytokine (tumour necrosis factor [TNF]-α) levels and bacterial species, in older patients.

Method:

This prospective study was conducted in a long-term care facility with patients whose PU had healed within two months. Biophysical skin properties were evaluated by stratum corneum hydration, pH, sebum content and transepidermal water loss. TNF-α level was measured using skin blotting. Skin bacteria were collected using tape stripping and determined by species-specific gene amplification. These parameters, along with Braden scale and interface pressure, were evaluated every two weeks for a total period of eight weeks. A penalised generalised estimating equation analysis was used to determine the risk factors for recurrent PUs.

Results:

In total, 20 patients were included in this study, with 57 observations. Of these, recurrent PU was seen in eight observations. Elevation of pH (p=0.049; odds ratio [OR] per 1 unit=3.91, 95% confidence interval [CI]:1.01–15.15), presence of Acinetobacter spp. (p=0.039; OR versus culture-negative=6.28, 95%CI:1.10–35.86) and higher interface pressure (p=0.008; OR per 1 mmHg=1.06, 95%CI:1.01–1.10) on the healed PU were significantly related to the development of recurrent PU.

Conclusion:

Higher pH, existence of Acinetobacter spp. and higher interface pressure on the site of the healed PU were associated with the development of recurrent PUs in older patients undergoing conservative treatments.

Moist-Retaining, Self-Recoverable, Bioadhesive, and Transparent in Situ Forming Hydrogels To Accelerate Wound Healing

In the management of accelerating wound healing, moist environments play an important role. Compared with other scaffolds of various forms, hydrogels can maintain a moist environment in the wound area. They are cross-linked hydrophilic polymeric networks that resemble natural soft tissues and extracellular matrices. Among them, injectable hydrogels have attracted great attention in wound repair, as they can be injected into irregular-shaped skin defects and formed in situ to shape the contour of different dimensions. The excellent compliance makes hydrogels easy to adapt to the wound under different conditions of skin movement. Here, we oxidized hydroxyethyl starch (O-HES) and modified carboxymethyl chitosan (M-CMCS) to fabricate an in situ forming hydrogel with excellent self-recoverable extensibility-compressibility, biocompatibility, biodegradability, and transparency for accelerating wound healing. The oxidation degree of O-HES was 74%. The amino modification degree of M-CMCS was 63%. M-CMCS/O-HES hydrogels were formed through the Schiff base reaction. The physicochemical properties of M-CMCS/O-HES hydrogels with various ratios were investigated, and M-CMCS/O-HES hydrogel with a volume ratio of 5:5 exhibited appropriate gelation time, notable water-retaining capacity, self-recoverable conformal deformation, suitable biodegradability, and good biocompatibility for wound-healing application. Then, skin wound-healing experimental studies were carried out in Sprague-Dawley rats with full-thickness skin defects. Significant outcomes were achieved in the M-CMCS/O-HES hydrogel-treated group including higher wound closure percentage, more granulation tissue formation, faster epithelialization, and decreased collagen deposition. These findings demonstrate that using the obtained M-CMCS/O-HES hydrogels is a promising therapeutic strategy for wound healing.

Adipose-Derived Tissue in the Treatment of Dermal Fibrosis: Antifibrotic Effects of Adipose-Derived Stem Cells

Treatment of hypertrophic scars and other fibrotic skin conditions with autologous fat injections shows promising clinical results; however, the underlying mechanisms of its antifibrotic action have not been comprehensively studied. Adipose-derived stem cells, or stromal cell-derived factors, inherent components of the transplanted fat tissue, seem to be responsible for its therapeutic effects on difficult scars. The mechanisms by which this therapeutic effect takes place are diverse and are mostly mediated by paracrine signaling, which switches on various antifibrotic molecular pathways, modulates the activity of the central profibrotic transforming growth factor β/Smad pathway, and normalizes functioning of fibroblasts and keratinocytes in the recipient site. Direct cell-to-cell communications and differentiation of cell types may also play a positive role in scar treatment, even though they have not been extensively studied in this context. A more thorough understanding of the fat tissue antifibrotic mechanisms of action will turn this treatment from an anecdotal remedy to a more controlled, timely administered technology.

Down-Regulation of MHC Class I Expression in Human Keratinocytes Using Viral Vectors Containing US11 Gene of Human Cytomegalovirus and Cultivation on Bovine Collagen-Elastin Matrix (Matriderm®): Potential Approach for an Immune-Privileged Skin Substitute

Skin transplantation, especially in burn patients, is still challenging because surgeons are faced with limited disposability of autologous donor side material. The in vitro culture of keratinocytes has become an important reconstructive option. However, only non-immunogenic allogenic keratinocytes offer the opportunity to develop a skin graft that can overcome rejection. The purpose of the study was to develop targeted gene modification of keratinocytes in order to reduce immunogenicity for the use as allogenic transplantable skin graft by decreasing the expression of MHC class I. To reduce MHC class I expression, viral vectors containing the US11 gene of human cytomegalovirus were generated and tested on their functionality using Western blotting, indirect immunofluorescence staining, and flow cytometry. Transfected keratinocytes were seeded on commercially available bovine collagen-elastin matrices and further cultured for histological and cell survival assays. Results showed transient down-regulation of MHC class I after 24 h post-transfection, with recovery of MHC class I expression after 48 h. Histological assessments showed long-term cell survival as well as histological patterns comparable to epidermal layers of healthy human skin. The data postulates the potential application of US11 transfected keratinocytes as an approach towards an immune-privileged skin substitute. Nevertheless, further studies and data are needed.

Topical Application of Culture-Expanded CD34+ Umbilical Cord Blood Cells from Frozen Units Accelerates Healing of Diabetic Skin Wounds in Mice

Chronic and nonhealing wounds are constant health issues facing patients with type 2 diabetes. As the incidence of type 2 diabetes mellitus (T2DM) increases, the incidence of chronic wounds and amputations will rise. T2DM is associated with peripheral arterial occlusive disease, which leads to the development of nonhealing skin ulcers after minor trauma. Patients develop severe pain limiting their mobility and ability to work and take care of themselves, thus putting a significant burden on the family and society. CD34+ cells from umbilical cord blood (UCB) grown in fibroblast growth factor-4 (FGF-4), stem cell factor, and Flt3-ligand produced a population of cells that have the ability to proliferate and develop properties enabling them to enhance tissue regeneration. The goal of this study was to assess in vitro cultured CD34+ cells in a setting where they would eventually be rejected so we could isolate paracrine signaling mediated therapeutic effect from the therapeutic effect due to engraftment and differentiation. To achieve this, we used db/db mice as a model for diabetic skin ulcers. Here, we report that in vitro cultured UCB CD34+ cells from frozen units can accelerate wound healing and resulted in the regeneration of full thickness skin. This study demonstrates a new indication for banked UCB units in the area of tissue regeneration. Stem Cells Translational Medicine 2018;7:591-601.

Production-scale fibronectin nanofibers promote wound closure and tissue repair in a dermal mouse model

Wounds in the fetus can heal without scarring. Consequently, biomaterials that attempt to recapitulate the biophysical and biochemical properties of fetal skin have emerged as promising pro-regenerative strategies. The extracellular matrix (ECM) protein fibronectin (Fn) in particular is believed to play a crucial role in directing this regenerative phenotype. Accordingly, Fn has been implicated in numerous wound healing studies, yet remains untested in its fibrillar conformation as found in fetal skin. Here, we show that high extensional (∼1.2 ×10⁵ s^-1) and shear (∼3 ×10⁵ s^-1) strain rates in rotary jet spinning (RJS) can drive high throughput Fn fibrillogenesis (∼10 mL/min), thus producing nanofiber scaffolds that are used to effectively enhance wound healing. When tested on a full-thickness wound mouse model, Fn nanofiber dressings not only accelerated wound closure, but also significantly improved tissue restoration, recovering dermal and epidermal structures as well as skin appendages and adipose tissue. Together, these results suggest that bioprotein nanofiber fabrication via RJS could set a new paradigm for enhancing wound healing and may thus find use in a variety of regenerative medicine applications.