Peripheral Blood Fibrocytes: Enhancement of Wound Healing by Cell Proliferation, Re-Epithelialization, Contraction, and Angiogenesis

OxInflammation Affects Transdifferentiation to Myofibroblasts, Prolonging Wound Healing in Diabetes: A Systematic Review

Skin wounds, primarily in association with type I diabetes mellitus, are a public health problem generating significant health impacts. Therefore, identifying the main pathways/mechanisms involved in differentiating fibroblasts into myofibroblasts is fundamental to guide research into effective treatments. Adopting the PRISMA guidelines, this study aimed to verify the main pathways/mechanisms using diabetic murine models and analyze the advances and limitations of this area. The Medline (PubMed), Scopus, and Web of Science platforms were used for the search. The studies included were limited to those that used diabetic murine models with excisional wounds. Bias analysis and methodological quality assessments were undertaken using the SYRCLE bias risk tool. Eighteen studies were selected. The systematic review results confirm that diabetes impairs the transformation of fibroblasts into myofibroblasts by affecting the expression of several growth factors, most notably transforming growth factor beta (TGF-beta) and NLRP3. Diabetes also compromises pathways such as the SMAD, c-Jun N-terminal kinase, protein kinase C, and nuclear factor kappa beta activating caspase pathways, leading to cell death. Furthermore, diabetes renders the wound environment highly pro-oxidant and inflammatory, which is known as OxInflammation. As a consequence of this OxInflammation, delays in the collagenization process occur. The protocol details for this systematic review were registered with PROSPERO: CRD42021267776.

Lithium chloride promotes mesenchymal-epithelial transition in murine cutaneous wound healing via inhibiting CXCL9 and IGF2

Cutaneous wound healing is a challenge in plastic and reconstructive surgery. In theory, cells undergoing mesenchymal transition will achieve re-epithelialization through mesenchymal-epithelial transition at the end of wound healing. But in fact, some pathological stimuli will inhibit this biological process and result in scar formation. If mesenchymal-epithelial transition can be activated at the corresponding stage, the ideal wound healing may be accomplished. Two in vivo skin defect mouse models and dermal-derived mesenchymal cells were used to evaluate the effect of lithium chloride in wound healing. The mesenchymal-epithelial transition was detected by immunohistochemistry staining. In vivo, differentially expressed genes were analysed by transcriptome analyses and the subsequent testing was carried out. We found that lithium chloride could promote murine cutaneous wound healing and facilitate mesenchymal-epithelial transition in vivo and in vitro. In lithium chloride group, scar area was smaller and the collagen fibres are also orderly arranged. The genes related to mesenchyme were downregulated and epithelial mark genes were activated after intervention. Moreover, transcriptome analyses suggested that this effect might be related to the inhibition of CXCL9 and IGF2, subsequent assays demonstrated it. Lithium chloride can promote mesenchymal-epithelial transition via downregulating CXCL9 and IGF2 in murine cutaneous wound healing, the expression of IGF2 is regulated by β-catenin. It may be a potential promising therapeutic drug for alleviating postoperative scar and promoting re-epithelialization in future.

Comparable Effects on Healing between Autologous Diabetic Adipose-Derived Stem Cells and Allogeneic Normal Counterparts

BACKGROUND

Adipose-derived stem cell (ASC) therapy is considered a promising strategy for improving impaired wound healing, especially in diabetics. Although the therapeutic potential of allogeneic ASCs from healthy donors is naturally limited, that of autologous ASCs from diabetic patients is questionable. The aim of this study was to investigate the impact of diabetic ASCs in the treatment of diabetic wounds.

METHODS

Diabetic ASCs (DMA) and nondiabetic ASCs were isolated from db/db and C57BL/6J mice, and characterized by immunocytochemistry, proliferation, differentiation, and gene expression assays. The effects of both ASCs on healing were investigated using 36 male 10- to 12-week-old db/db mice. Wound size was measured semiweekly until day 28, and histologic and molecular analyses were performed at day 14.

RESULTS

Both ASCs had fibroblast-like morphology and were CD44 + /CD90 + /CD34 - /CD45 - at passage 4. Compared with nondiabetic ASCs in vitro, DMA proliferative capability was restored by passage 4 ( P > 0.05). Although DMA osteogenesis was attenuated ( P < 0.01), both ASCs had similar adipogenesis and expressions of PPARγ/LPL/OCN/RUNX2 ( P > 0.05). In vivo experiments showed that, compared with phosphate-buffered saline control, both ASCs are comparable in improving wound healing ( P < 0.0001), angiogenesis ( P < 0.05), epithelial cell proliferation ( P < 0.05), and granulation tissue formation ( P < 0.0001).

CONCLUSIONS

In both in vitro and in vivo murine models, DMAs have shown a comparable therapeutic capacity to normal ASCs in promoting diabetic wound healing by improving angiogenesis, reepithelialization, and granulation tissue formation. These results support clinical applications of autologous ASCs in diabetic wound treatments.

CLINICAL RELEVANCE STATEMENT

This work has particular surgical relevance as it highlights a theoretical and clinical pathway to use diabetic patients' own ASCs to treat their wounds, bypassing any concerns of cross-host sourcing issues in regenerative medicine.

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Fibroblast Viability Through Mechanical and Chemical Root Surface Modifications in Periodontal Healing: An In Vitro Comparative Study

BACKGROUND

The wound-healing process incorporates a spectrum of periodontal therapeutic interventions that strive to restore the health and function of the periodontium. Fibroblasts play pivotal roles in tissue repair and regeneration. Extensive research has been focused on mechanical and chemical root surface modifications to enhance fibroblast adhesion, which is crucial for successful wound healing.

PURPOSE

This study aimed to assess the combined efficacy of mechanical and chemical root surface modifications in promoting fibroblast viability to root surfaces affected by periodontitis in comparison to chemical modifications alone.

MATERIALS AND METHODS

Root samples were collected from healthy individuals and those with advanced periodontitis. The specimens were prepared, and the experimental groups were categorized based on the type of surface modification with mechanical and/or chemical materials, including hyaluronic acid (HA), ethylenediaminetetraacetic acid (EDTA), enamel matrix derivatives (EMD), and EDTA/EMD. Fibroblasts were seeded onto previously treated root samples. Cell adhesion was assessed using a viability assay.

RESULTS

Fibroblast viability was significantly higher on root surfaces treated with chemical agents than on those treated with mechanical and chemical modifications. Long-duration EDTA and short-duration EMD treatments were significantly effective in enhancing cell viability. EDTA/EMD surface treatments resulted in significantly higher cell viability in all groups compared to the periodontitis root surfaces.

CONCLUSION

EDTA, EMD, and their combined application can potentially ameliorate periodontitis-induced surface structural impairments. Mechanical surface debridement can significantly affect the effectiveness of EDTA and EMD root conditioning agents.

Serum Amyloid P Attenuates Hypertrophic Scarring in Large Animal Models

INTRODUCTION

This study's purpose was to (1)determine the effect of locally administered serum amyloid P (SAP) on the development of hypertrophic scars (HTS) in porcine and rabbit HTS models and (2)determine the pharmacokinetics of systemically administered SAP and its effect on circulating fibrocyte quantities.

METHODS

Two large animal (New Zealand White Rabbit and Female Red Duroc Pigs) HTS models were utilized to study the effects of daily local injections of SAP immediately post wounding (x5 d in rabbits; x7 d in pigs) on HTS development as measured by scar elevation index , scar area, wound closure, and molecular expression studies of scar components. For SAP pharmacokinetics, total and human SAP levels in porcine blood were measured at regular intervals following intravenous administration of human SAP. Fibrocyte quantities were determined prior to and 1 h following human SAP intravenous administration.

RESULTS

In the rabbit model, local SAP significantly decreased the level of tissue inhibitor of metalloproteinases-1 mRNA expression and maintained matrix mettaloproteinase-9 expression, while control and vehicle groups significantly declined. In the pig model, there was a significant decrease in the trend of scar elevation indexes treated with local SAP versus controls over the study period. This decrease was statistically significant at days 14 and 84. Human SAP administered intravenously is degraded within 24 h and does not influence circulating fibrocyte quantities.

CONCLUSIONS

This is the first study to demonstrate attenuation of HTS formation using locally administered SAP in large animal HTS models. Local SAP administration reduces HTS formation by maintaining matrix mettaloproteinase-9 and decreasing tissue inhibitor of metalloproteinases-1. Intravenous administration of SAP is not as effective.

Synergistic effect of Mn-Si-COS on wound immune microenvironment by inhibiting excessive skin fibrosis mediated with ROS/TGF-β1/Smad7 signal

Excessive oxidative stress and inflammation often impede wound healing and ultimately lead to excessive skin fibrosis formation. It was known that the structural properties of biomaterials can affect the healing and immune response of surrounding tissues. In this work, a composite structure of Mn-Si-chitooligosaccharides (COS) was designed (COS@Mn-MSN) and the ability of regulating wound microenvironment for inhibiting skin fibrosis was investigated. In order to reduce the negative effects of Mn, the nano-level Mn was doped into MSN to minimize its content. The results show that Mn in COS@Mn-MSN showed significant ability of scavenging excess intracellular ROS within 1 d. The Si released from COS@Mn-MSN can shift M2 macrophage polarization in the later stage (1-3 d), showing anti-inflammatory effect. Macrophage (RAW264.7) were activated alternatively by COS released from COS@Mn-MSN, with upregulated expression of anti-inflammatory factors (IL-10 and CD206) and downregulated expression of pro-inflammatory factors (TNF-α, CD80, and IL-1β) in the whole time. The expression of fibrosis associated factor TGF-β1 and CD26 in fibroblast cells (L929) were inhibited by COS and Si. Besides, the inflammatory microenvironment mediated by COS@Mn-MSN downregulated Smad-7 gene expression and upregulated Col-1α gene expression. With the function of reducing oxidative stress (0-1 d), the TGF-β1 inhibition (1-3 d) and anti-inflammatory effects (0-3 d), COS@Mn-MSN could inhibit excessive skin fibrosis formation mediated with ROS/TGF-β1/Smad7 signal. Therefore, the prepared COS@Mn-MSN shows great potential to active scarless wound therapy.

Topically Applied Biopolymer-Based Tri-Layered Hierarchically Structured Nanofibrous Scaffold with a Self-Pumping Effect for Accelerated Full-Thickness Wound Healing in a Rat Model

Wound healing has grown to be a significant problem at a global scale. The lack of multifunctionality in most wound dressing-based biopolymers prevents them from meeting all clinical requirements. Therefore, a multifunctional biopolymer-based tri-layered hierarchically nanofibrous scaffold in wound dressing can contribute to skin regeneration. In this study, a multifunctional antibacterial biopolymer-based tri-layered hierarchically nanofibrous scaffold comprising three layers was constructed. The bottom and the top layers contain hydrophilic silk fibroin (SF) and fish skin collagen (COL), respectively, for accelerated healing, interspersed with a middle layer of hydrophobic poly-3-hydroxybutyrate (PHB) containing amoxicillin (AMX) as an antibacterial drug. The advantageous physicochemical properties of the nanofibrous scaffold were estimated by SEM, FTIR, fluid uptake, contact angle, porosity, and mechanical properties. Moreover, the in vitro cytotoxicity and cell healing were assessed by MTT assay and the cell scratching method, respectively, and revealed excellent biocompatibility. The nanofibrous scaffold exhibited significant antimicrobial activity against multiple pathogenic bacteria. Furthermore, the in vivo wound healing and histological studies demonstrated complete wound healing in wounded rats on day 14, along with an increase in the expression level of the transforming growth factor-β1 (TGF-β1) and a decrease in the expression level of interleukin-6 (IL-6). The results revealed that the fabricated nanofibrous scaffold is a potent wound dressing scaffold, and significantly accelerates full-thickness wound healing in a rat model.

Jia-Wei-Si-Miao-Yong-An Fang stimulates the healing of acute radiation-induced cutaneous wounds through MAPK/ERK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

A famous traditional oral Chinese medicine formula, Si-Miao-Yong-An decoction, has been used to treat thromboangiitis obliterans from the Qing Dynasty. Because its therapeutic principles including clearing away heat, detoxification, accelerating blood circulation and relieving pains are consistent with acute radiation-induced cutaneous wounds in traditional Chinese medicine, we tried to add herbs and improve them into an external dosage form, called Jia-Wei-Si-Miao-Yong-An Fang (JWSMYA). However, its mechanism on radiation-induced cutaneous wounds is still unknown.

AIM OF THE STUDY

This study evaluated the therapeutic effect of JWSMYA and investigated the mechanism of repair and anti-fibrosis on acute radiation-induced cutaneous wounds with JWSMYA.

MATERIALS AND METHODS

Firstly, we prepared JWSMYA, and determined the composition through UHPLC LC-MS/MS. Then we used ionizing radiation to make a cutaneous wound model of rats, and observed wound healing through their skin injury score, wound contraction percentage and histological staining. In addition, immunohistochemical staining, Western blot analysis, qRT-PCR and Elisa were used to explore wound rehabilitation and anti-fibrosis mechanisms.

RESULTS

An in vivo assay revealed that JWSMYA promoted the repairment of acute radiation-induced cutaneous wounds, facilitated MAPK/ERK phosphorylation, inhibited PI3K/AKT activation, reduced the level of alpha-smooth muscle actin (a-sma), collagen type-I alpha 2 (Col1a2) and transforming growth factor-beta 1 (TGF-β1) in cutaneous tissues. However, no statistical difference was found in vascular endothelial growth factor (VEGF).

CONCLUSION

JWSMYA accelerated the repair of acute radiation-induced cutaneous wounds, which might be associated with the MAPK/ERK pathway. In addition, PI3K/AKT might be associated with the inhibition of fibrosis and the promotion of high-quality wound healing.

All-in-one bioactive properties of photothermal nanofibers for accelerating diabetic wound healing

Diabetic wound healing has attracted widespread attention in biomedical engineering. However, the harsh hypoxic microenvironment (HME) comprising high glucose levels, local bleeding, and bacterial infection often leads to the formation of hyperplastic scars, increasing the clinical demand for wound dressings. Here, we report a comprehensive strategy using near-infrared NIR-assisted oxygen delivery combined with the bioactive nature of biopolymers for remodeling the HME. Black phosphorus (BP) nanosheets and hemoglobin (Hb) were self-assembled layerwise onto electrospun poly-l-lactide (PLLA) nanofibers using charged quaternized chitosan (QCS) and hyaluronic acid. BP converts NIR radiation into heat and stimulates Hb to release oxygen in situ. QCS is a hemostatic and broad-spectrum antibacterial material. Moderate BP-derived photothermal therapy can increase the sensitivity of bacteria to QCS. A series of composite wound dressings (coded as PQBH-n) with different numbers of layers were fabricated, and the in vivo diabetic wound healing potentials were tested. The molecular mechanism can be partly attributed to the cytokine-cytokine receptor interaction. Notably, this comprehensive strategy based on NIR-assisted oxygen delivery combined with the bioactive properties of biopolymers is not only applicable for fabricating multifunctional wound dressings but also has a great potential in expanding biomedical engineering fields.

Sex difference on fibroblast growth factors (FGFs) expression in skin and wound of streptozotocin(STZ)-induced type 1 diabetic mice

BACKGROUND

Fibroblast growth factors (FGFs) are key factors affecting diabetic wound healing. However, the FGF family's expression patterns in skin and wounds influenced by both diabetes and sex are still unknown.

METHODS AND RESULTS

In this study, normal and Streptozotocin (STZ)-induced type 1 diabetic C57BL/6J male and female mice were used to study the FGF family's expression in non-wound skin and wounds. We found that the expression patterns of Fgfs were affected by sex in both normal and diabetic animals during wound healing. In normal control mice, sex difference had a limited effect on basal skin Fgf expressions. However, it significantly influenced Fgf expressions in wounds. Type 1 diabetes reduced basal and wound-induced skin Fgf expressions. Female mice had far lower wound-induced skin Fgf expressions in diabetic mice. In addition, sex differently influenced Fibroblast growth factors receptor (Fgfr) expression patterns of non-wound skin and wounds in both normal and diabetic mice. Moreover, female mice had a lower relative level of Fibronectin leucine-rich repeat transmembrane protein 2 (FLRT2) - a FGFR activation marker gene - in wound and blood plasma. Correspondingly, the wound areas of female animals were larger than that of male animals in the early stage of wound healing (less than 3-day injury).

CONCLUSION

Our research shows that the FGF family have different expression patterns in normal and diabetic wound healing in mice of different sex. Additionally, we also provide the signatures of individual FGFs in diabetic wound healing, which deserve further investigation.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

Effects of microRNAs on angiogenesis in diabetic wounds

Diabetes mellitus is a morbid condition affecting a growing number of the world population, and approximately one third of diabetic patients are afflicted with diabetic foot ulcers (DFU), which are chronic non-healing wounds that frequently progress to require amputation. The treatments currently used for DFU focus on reducing pressure on the wound, staving off infection, and maintaining a moist environment, but the impaired wound healing that occurs in diabetes is a constant obstacle that must be faced. Aberrant angiogenesis is a major contributor to poor wound healing in diabetes and surgical intervention is often necessary to establish peripheral blood flow necessary for healing wounds. Over recent years, microRNAs (miRNAs) have been implicated in the dysregulation of angiogenesis in multiple pathologies including diabetes. This review explores the pathways of angiogenesis that become dysregulated in diabetes, focusing on miRNAs that have been identified and the mechanisms by which they affect angiogenesis.

Chitosan-based microneedle arrays for dermal delivery of Centella Asiatica

Centella asiatica, a medicinal herb used for wound healing, has a limited effect when delivered as an ointment. Centella asiatica's active component asiatic acid (AA) increases extracellular matrix development and reduces inflammation but cannot penetrate the stratum corneum to access deeper skin layers. To bypass the stratum corneum, we formulated two types of AA-loaded microneedle arrays. We fabricated, characterised and optimised a dissolving array made from chitosan and PVA and a hydrogel array made from chitosan and PVP. Both needles were strong and long enough to pierce the epidermis without breaking. Both were biocompatible with keratinocytes and fibroblasts (>75% viability at 100% concentration) and showed a sustained drug release over 48 hours. The hydrogel microneedle released more AA (52.2%) than the dissolving formulation (26.4%); thus, we evaluated them in an excisional rat model. The hydrogel microneedle arrays significantly increased the rate of wound closure compared to the control. This research has shown that the chitosan-PVA hydrogel microneedles could penetrate the epidermis, effectively release AA, and increase the wound closure rate. This AA-loaded delivery system shows promise as a natural treatment for wound healing and may be applied to other bioactive compounds with similar physiochemical properties in the future.

M-CSF-stimulated myeloid cells can convert into epithelial cells to participate in re-epithelialization and hair follicle regeneration during dermal wound healing

Dermal wound healing is a complex process which requires the interaction of many cell types and mediators in a highly sophisticated temporal sequence. Myeloid cells which compose of a significant proportion of the inflammatory cells infiltrate to the to a wound site where they play important roles in clearance of damaged tissue and microorganisms. Myeloid cells have the capacity to be converted into fibroblast-like cells and endothelial cells during wound healing process. However, whether myeloid cells in wounds can convert into epithelial cells where they contribute to healing process is not clear. In this study, we performed double immunofluorescent staining with antibodies for hematopoietic cells and keratinocytes as well as cell tracing technique to investigate hematopoietic cell conversion. The result showed that during the healing process, some of the CD45-positive hematopoietic cells also expressed keratin 14, a marker for keratinocytes. Further, double immunofluorescent staining in dermal wounds, using CD11b and K14 antibodies indicated that CD11b-positive myeloid cells were the origin of newly generated epithelial cells. Through tracing injected labeled splenocyte-derived myeloid cells in skin, we confirmed that myeloid cells were able to convert into keratinocytes in repaired skin. Furthermore, our results from in vivo experiments provided new information on contribution of myeloid cells in hair follicle regeneration. In conclusion, this work highlights the myeloid cell contributions in wound repair and hair follicle regeneration through conversion of M-CSF-stimulated CD11b-positive myeloid cells into epithelial cells in a murine model.

Therapeutic Potential of Exosomes Derived from Diabetic Adipose Stem Cells in Cutaneous Wound Healing of db/db Mice

(1) Background: Diabetes impairs angiogenesis and wound healing. Paracrine secretion from adipose stem cells (ASCs) contains membrane-bound nano-vesicles called exosomes (ASC-Exo) but the functional role and therapeutic potential of diabetic ASC-Exo in wound healing are unknown. This study aims to investigate the in vivo mechanistic basis by which diabetic ASC-Exo enhance cutaneous wound healing in a diabetic mouse model. (2) Methods: Topically applied exosomes could efficiently target and preferentially accumulate in wound tissue, and the cellular origin, ASC or dermal fibroblast (DFb), has no influence on the biodistribution pattern of exosomes. In vivo, full-thickness wounds in diabetic mice were treated either with ASC-Exo, DFb-Exo, or phosphate-buffered saline (PBS) topically. ASC-Exo stimulated wound healing by dermal cell proliferation, keratinocyte proliferation, and angiogenesis compared with DFb-Exo and PBS-treated wounds. (3) Results: Diabetic ASC-Exo stimulated resident monocytes/macrophages to secrete more TGF-β1 and activate the TGF-β/Smad3 signaling pathway. Fibroblasts activated by TGF-β1containing exosomes from ASCs initiate the production of TGF-β1 protein in an autocrine fashion, which leads to more proliferation and activation of fibroblasts. TGF-β1 is centrally involved in diabetic ASC-Exo mediated cellular crosstalk as an important early response to initiating wound regeneration. (4) Conclusions: The application of diabetic ASC-Exo informs the potential utility of a cell-free therapy in diabetic wound healing.

Comparison of Yield, Purity, and Functional Properties of Large-Volume Exosome Isolation Using Ultrafiltration and Polymer-Based Precipitation

BACKGROUND

Mesenchymal stem cell-derived exosomes are known to produce effects similar to those of source cells and therefore represent a new approach in cell-free regenerative medicine. Their potential clinical application demands efficient isolation of stable and functional exosomes from a large volume of biological fluid.

METHODS

Exosomes from adipose-tissue conditioned medium of the same volume were isolated using either (1) ultrafiltration with size exclusion or (2) ExoQuick-TC. The isolated exosomes were characterized by protein concentration, particle size, exosomal marker expression, RNA expression profiles, and roles in dermal fibroblast proliferation and migration.

RESULTS

Both isolation methods produced exosomes within the size range defined for exosomes (50 to 200 nm) and common markers were enriched. Compared to the ExoQuick-TC precipitation method, the ultrafiltration method produced a significantly higher protein yield (p < 0.001) but a lower particle-to-protein ratio (p < 0.05); it also yielded higher RNA contents from the same fat tissue indicated by housekeeping genes, but with overall lower purity. The expression of several mRNAs and miRNAs related to tissue regeneration showed that there was no statistical difference between both methods, except miR-155 and miR-223 (p < 0.05). However, there was no difference in overall fibroblast proliferation and migration between exosomes isolated by these two methods.

CONCLUSIONS

Ultrafiltration with size exclusion demonstrated higher yields, acceptable purity, and comparable biophysical properties and biological functions to the more expensive commercial precipitation method. Therefore, it may conceivably be translated into yield-efficient and cost-effective modalities for therapeutic purposes.

CLINICAL RELEVANCE STATEMENT

Ultrafiltration with size exclusion may be amenable for exosome isolation from large-volume complex fluids such as tissue conditioned media for clinical application in future regenerative medicine.

A novel long-term intravenous combined with local treatment with human amnion-derived mesenchymal stem cells for a multidisciplinary rescued uremic calciphylaxis patient and the underlying mechanism

Calciphylaxis is a rare disease characterized histologically by microvessel calcification and microthrombosis, with high mortality and no proven therapy. Here, we reported a severe uremic calciphylaxis patient with progressive skin ischemia, large areas of painful malodorous ulcers, and mummified legs. Because of the worsening symptoms and signs refractory to conventional therapies, treatment with human amnion-derived mesenchymal stem cells (hAMSCs) was approved. Pre-clinical release inspections of hAMSCs, efficacy, and safety assessment including cytokine secretory ability, immunocompetence, tumorigenicity, and genetics analysis in vitro were introduced. We further performed acute and long-term hAMSC toxicity evaluations in C57BL/6 mice and rats, abnormal immune response tests in C57BL/6 mice, and tumorigenicity tests in neonatal Balbc-nu nude mice. After the pre-clinical research, the patient was treated with hAMSCs by intravenous and local intramuscular injection and external supernatant application to the ulcers. When followed up to 15 months, the blood-based markers of bone and mineral metabolism improved, with skin soft tissue regeneration and a more favorable profile of peripheral blood mononuclear cells. Skin biopsy after 1-month treatment showed vascular regeneration with mature non-calcified vessels within the dermis, and 20 months later, the re-epithelialization restored the integrity of the damaged site. No infusion or local treatment-related adverse events occurred. Thus, this novel long-term intravenous combined with local treatment with hAMSCs warrants further investigation as a potential regenerative treatment for uremic calciphylaxis with effects of inhibiting vascular calcification, stimulating angiogenesis and myogenesis, anti-inflammatory and immune modulation, multi-differentiation, re-epithelialization, and restoration of integrity.

Single-Cell Transcriptome Profiles Reveal Fibrocytes as Potential Targets of Cell Therapies for Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is potentially life-threatening in aging population due to the risk of aortic rupture and a lack of optimal treatment. The roles of different vascular and immune cells in AAA formation and pathogenesis remain to be future characterized. Single-cell RNA sequencing was performed on an angiotensin (Ang) II-induced mouse model of AAA. Macrophages, B cells, T cells, fibroblasts, smooth muscle cells and endothelial cells were identified through bioinformatic analyses. The discovery of multiple subtypes of macrophages, such as the re-polarization of Trem2⁺Acp5⁺ osteoclast-like and M2-like macrophages toward the M1 type macrophages, indicates the heterogenous nature of macrophages during AAA development. More interestingly, we defined CD45⁺COL1⁺ fibrocytes, which was further validated by flow cytometry and immunostaining in mouse and human AAA tissues. We then reconstituted these fibrocytes into mice with Ang II-induced AAA and found the recruitment of these fibrocytes in mouse AAA. More importantly, the fibrocyte treatment exhibited a protective effect against AAA development, perhaps through modulating extracellular matrix production and thus enhancing aortic stability. Our study reveals the heterogeneity of macrophages and the involvement of a novel cell type, fibrocyte, in AAA. Fibrocyte may represent a potential cell therapy target for AAA.

Healing Effect of Subcutaneous Administration of Granulocyte Colony-Stimulating Factor on Acute Rotator Cuff Injury in a Rat Model

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that mobilizes bone marrow-derived cells (BMDCs) to peripheral blood and has been clinically used to treat neutropenia. Previously, we reported that BMDCs migrated into the rotator cuff repair site via peripheral blood in the healing process. However, techniques to accelerate the healing process using the peripheral blood pathway have not been established. We evaluated whether G-CSF has a noteworthy effect on improving rotator cuff healing by enhancing the influx of BMDCs into the peripheral blood. We used Sprague-Dawley rats and chimeric rats, selectively expressing green fluorescent protein (GFP) in BMDCs. Their bilateral supraspinatus tendons were resected and sutured to the greater tuberosity of the humerus using the Masson-Allen technique, and G-CSF was subcutaneously injected for 5 days after surgery. Several GFP-positive cells were observed around the enthesis in the G-CSF-treated group compared with that in the Control group. Histological analysis revealed that the tendon-to-bone maturing scores and the Safranin O-stained cartilaginous areas were significantly higher in G-CSF-injected rats than in the control rats at weeks 4 and 8 after surgery. Consistently, the ultimate force to failure in the G-CSF-treated group significantly increased compared with the Control group at weeks 4 and 8 after surgery. These results suggest that BMDCs mobilized into the peripheral blood after G-CSF administration migrated to the rotator cuff repair area and effectively enhanced rotator cuff healing by promoting tenocyte and cartilage matrix production. In conclusion, the BMDC mobilization technique by G-CSF treatment via peripheral blood will provide a potential therapeutic approach for rotator cuff healing with clinically relevant applications. Impact statement As the retear rate following rotator cuff repair is high, new methods to aid its healing are required. Granulocyte colony-stimulating factor (G-CSF) has been used clinically and may represent a novel approach to treating rotator cuff tear. Herein, using a rat model, we elucidate the kinetics of bone marrow-derived mesenchymal stem cells at the repair site following G-CSF administration and describe the underlying mechanism by which G-CSF can help promote the repair of the rotator cuff.

Evolving Perspectives on Innate Immune Mechanisms of IPF

While epithelial-fibroblast interactions are viewed as the primary drivers of Idiopathic Pulmonary Fibrosis (IPF), evidence gleaned from animal modeling and human studies implicates innate immunity as well. To provide perspective on this topic, this review synthesizes the available data regarding the complex role of innate immunity in IPF. The role of substances present in the fibrotic microenvironment including pathogen associated molecular patterns (PAMPs) derived from invading or commensal microbes, and danger associated molecular patterns (DAMPs) derived from injured cells and tissues will be discussed along with the proposed contribution of innate immune populations such as macrophages, neutrophils, fibrocytes, myeloid suppressor cells, and innate lymphoid cells. Each component will be considered in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

Wound healing applications of creams and "smart" hydrogels

Although superficial wounds are often easy to treat for healthy individuals, there are some more severe types of wounds (burns, ulcers, diabetic wounds, etc.) that are a challenge for clinicians. A good therapeutic result is based on the delivery of a treatment at the right time, for the right patient. Our goal was to sum up useful knowledge regarding wound healing and wound treatments, based on creams and hydrogels with various active ingredients. We concluded that both preparations have application in preventing infections and promoting healing, but their efficacy is clearly conditioned by the type, depth, severity of the wound and patient profile. However, due to their superior versatility and capability of maintaining the integrity and functionality of the active ingredient, as well as it is controlled release at site, hydrogels are more suited for incorporating different active ingredients. New wound healing devices can combine smart hydrogel dressings with physical therapies to deliver a more efficient treatment to patients if the indications are appropriate.

Experimental Study on the Effect of Allogeneic Endothelial Progenitor Cells on Wound Healing in Diabetic Mice

Endothelial progenitor cells (EPCs) are involved in the neovascularization in traumatic and ischemic sites, but EPCs are "detained" in bone marrow under diabetic conditions, which results in reduction of the number of EPCs and their biological activity in peripheral blood. Based on our previous study to mobilize autologous bone marrow EPCs by administering AMD3100+G-CSF to realize the optimal effect, our present study is aimed at exploring the effects of transplanting EPCs locally in a wound model of diabetic mice. First, we prepared and identified EPCs, and the biological functions and molecular characteristics were compared between EPCs from DB/+ and DB/DB mice. Then, we performed full-thickness skin resection in DB/DB mice and tested the effect of local transplantation of EPCs on skin wound healing. The wound healing process was recorded using digital photographs. The animals were sacrificed on postoperative days 7, 14, and 17 for histological and molecular analysis. Our results showed that DB/+ EPCs were biologically more active than those of DB/DB EPCs. When compared with the control group, local transplantation of EPCs accelerated wound healing in DB/DB mice by promoting wound granulation tissue formation, angiogenesis, and collagen fiber deposition, but there was no significant difference in wound healing between DB/+ EPCs and DB/DB EPCs transplanted into the wound. Furthermore, local transplantation of EPCs promoted the expression of SDF-1, CXCR4, and VEGF. We speculated that EPC transplantation may promote wound healing through the SDF-1/CXCR4 axis. This point is worth exploring further. Present data are of considerable significance because they raise the possibility of promoting wound healing by isolating autologous EPCs from the patient, which provides a new approach for the clinical treatment of diabetic wounds in the future.

Fibroblast Growth Factor in Diabetic Foot Ulcer: Progress and Therapeutic Prospects

Diabetic foot ulcer (DFU) is a combination of neuropathy and various degrees of peripheral vasculopathy in diabetic patients resulting in lower extremity infection, ulcer formation, and deep-tissue necrosis. The difficulty of wound healing in diabetic patients is caused by a high glucose environment and various biological factors in the patient. The patients' skin local microenvironment changes and immune chemotactic response dysfunction. Wounds are easy to be damaged and ulcerated repeatedly, but difficult to heal, and eventually develop into chronic ulcers. DFU is a complex biological process in which many cells interact with each other. A variety of growth factors released from wounds are necessary for coordination and promotion of healing. Fibroblast growth factor (FGF) is a family of cell signaling proteins, which can mediate various processes such as angiogenesis, wound healing, metabolic regulation and embryonic development through its specific receptors. FGF can stimulate angiogenesis and proliferation of fibroblasts, and it is a powerful angiogenesis factor. Twenty-three subtypes have been identified and divided into seven subfamilies. Traditional treatments for DFU can only remove necrotic tissue, delay disease progression, and have a limited ability to repair wounds. In recent years, with the increasing understanding of the function of FGF, more and more researchers have been applying FGF-1, FGF-2, FGF-4, FGF-7, FGF-21 and FGF-23 topically to DFU with good therapeutic effects. This review elaborates on the recently developed FGF family members, outlining their mechanisms of action, and describing their potential therapeutics in DFU.

Extreme Diversity of the Human Vascular Mesenchymal Cell Landscape

Background Human mesenchymal cells are culprit factors in vascular (patho)physiology and are hallmarked by phenotypic and functional heterogeneity. At present, they are subdivided by classic umbrella terms, such as "fibroblasts," "myofibroblasts," "smooth muscle cells," "fibrocytes," "mesangial cells," and "pericytes." However, a discriminative marker-based subclassification has to date not been established. Methods and Results As a first effort toward a classification scheme, a systematic literature search was performed to identify the most commonly used phenotypical and functional protein markers for characterizing and classifying vascular mesenchymal cell subpopulation(s). We next applied immunohistochemistry and immunofluorescence to inventory the expression pattern of identified markers on human aorta specimens representing early, intermediate, and end stages of human atherosclerotic disease. Included markers comprise markers for mesenchymal lineage (vimentin, FSP-1 [fibroblast-specific protein-1]/S100A4, cluster of differentiation (CD) 90/thymocyte differentiation antigen 1, and FAP [fibroblast activation protein]), contractile/non-contractile phenotype (α-smooth muscle actin, smooth muscle myosin heavy chain, and nonmuscle myosin heavy chain), and auxiliary contractile markers (h1-Calponin, h-Caldesmon, Desmin, SM22α [smooth muscle protein 22α], non-muscle myosin heavy chain, smooth muscle myosin heavy chain, Smoothelin-B, α-Tropomyosin, and Telokin) or adhesion proteins (Paxillin and Vinculin). Vimentin classified as the most inclusive lineage marker. Subset markers did not separate along classic lines of smooth muscle cell, myofibroblast, or fibroblast, but showed clear temporal and spatial diversity. Strong indications were found for presence of stem cells/Endothelial-to-Mesenchymal cell Transition and fibrocytes in specific aspects of the human atherosclerotic process. Conclusions This systematic evaluation shows a highly diverse and dynamic landscape for the human vascular mesenchymal cell population that is not captured by the classic nomenclature. Our observations stress the need for a consensus multiparameter subclass designation along the lines of the cluster of differentiation classification for leucocytes.

The Pathobiology of Skin Aging: New Insights into an Old Dilemma

Long considered both physiologic and inevitable, skin aging is a degenerative phenomenon whereby both intrinsic and environmental factors conspire to produce an authentic disease. The consequences of this disorder are many and varied, ranging from atrophy and fragility to defective repair to deficient immunity and vulnerability to certain infections. The pathobiologic basis for skin aging remains poorly understood. At a cellular level, stem cell dysfunction and attrition appear to be key events, and both genetic and epigenetic factors are involved in a complex interplay that over time results in deterioration of our main protective interface with the external environment. Past and current understanding of the cellular and molecular intricacies of skin aging provide a foundation for future approaches designed to thwart the aging phenotype. Herein, the authors provide a review of current insights into skin aging, including the mechanisms of skin aging, the role of stem cells in skin aging and the implications of skin aging for the microbiome and for the development of cancer. Conquest of the oft overlooked disease of skin aging should have broad implications that transcend the integument and inform novel approaches to retarding aging and age-related dysfunction in those internal organs that youthful skin was designed to envelop and safeguard.

Development and characterization of a superabsorbing hydrogel film containing Ulmus davidiana var. Japonica root bark and pullulan for skin wound healing

Ulmus davidiana var. japonica (UD) has widely been used in Korean traditional medicine for the treatment of various types of diseases including inflammation and skin wounds. The UD root bark powders possess gelling activity with an excellent capacity for absorbing water. This distinct property could make the UD root bark powders to be a great material for manufacturing a gel film specifically for the healing of large and highly exudating wounds (e.g., pressure sores and diabetic ulcers). In this research, we separated the UD root bark powder into 4 different samples based on their sizes and then tested their water absorption capacity and flowability. Based on these results, 75-150 μm sized and below 75 μm sized samples of UD root bark powders were chosen, and UD gel films were prepared. The UD gel films showed good thermal stability and mechanically improved properties compared with pullulan only gel film with excellent swelling capacity and favorable skin adhesiveness. Further, in the animal studies with the skin wound mice model, the UD gel films exhibited significant therapeutic effects on accelerating wound closure and dermal regeneration. Overall, this study demonstrated the applicability of UD root bark powders for hydrogel wound dressing materials, and the potential of UD gel films to be superior wound dressings to currently available ones.

The Vascular Involvement in Soft Tissue Fibrosis-Lessons Learned from Pathological Scarring

Soft tissue fibrosis in important organs such as the heart, liver, lung, and kidney is a serious pathological process that is characterized by excessive connective tissue deposition. It is the result of chronic but progressive accumulation of fibroblasts and their production of extracellular matrix components such as collagens. Research on pathological scars, namely, hypertrophic scars and keloids, may provide important clues about the mechanisms that drive soft tissue fibrosis, in particular the vascular involvement. This is because these dermal fibrotic lesions bear all of the fibrotic characteristics seen in soft tissue fibrosis. Moreover, their location on the skin surface means they are readily observable and directly treatable and therefore more accessible to research. We will focus here on the roles that blood vessel-associated cells play in cutaneous scar pathology and assess from the literature whether these cells also contribute to other soft tissue fibroses. These cells include endothelial cells, which not only exhibit aberrant functions but also differentiate into mesenchymal cells in pathological scars. They also include pericytes, hepatic stellate cells, fibrocytes, and myofibroblasts. This article will review with broad strokes the roles that these cells play in the pathophysiology of different soft tissue fibroses. We hope that this brief but wide-ranging overview of the vascular involvement in fibrosis pathophysiology will aid research into the mechanisms underlying fibrosis and that this will eventually lead to the development of interventions that can prevent, reduce, or even reverse fibrosis formation and/or progression.

The Blood Circulating Rare Cell Population. What is it and What is it Good For?

Blood contains a diverse cell population of low concentration hematopoietic as well as non-hematopoietic cells. The majority of such rare cells may be bone marrow-derived progenitor and stem cells. This paucity of circulating rare cells, in particular in the peripheral circulation, has led many to believe that bone marrow as well as other organ-related cell egress into the circulation is a response to pathological conditions. Little is known about this, though an increasing body of literature can be found suggesting commonness of certain rare cell types in the peripheral blood under physiological conditions. Thus, the isolation and detection of circulating rare cells appears to be merely a technological problem. Knowledge about rare cell types that may circulate the blood stream will help to advance the field of cell-based liquid biopsy by supporting inter-platform comparability, making use of biological correct cutoffs and “mining” new biomarkers and combinations thereof in clinical diagnosis and therapy. Therefore, this review intends to lay ground for a comprehensive analysis of the peripheral blood rare cell population given the necessity to target a broader range of cell types for improved biomarker performance in cell-based liquid biopsy.

Exosomes Are Comparable to Source Adipose Stem Cells in Fat Graft Retention with Up-Regulating Early Inflammation and Angiogenesis

BACKGROUND

Exosomes derived from mesenchymal stem cells possess functional properties similar to those of their parent cells, suggesting that they could play a pivotal role in tissue repair and regeneration.

METHODS

Using lipotransfer as a surrogate, exosomes were isolated from mouse adipose-derived stem cell-conditioned medium and characterized. Minced fat tissue mixed with exosomes, source cells (cell-assisted lipotransfer), or saline was implanted subcutaneously in the lower back of C57/BL mice bilaterally (n = 16 each). Transferred fat tissues were harvested and analyzed at 3 and 10 weeks.

RESULTS

At 3 and 10 weeks after the transfer, fat grafts in groups of exosomes and cell-assisted lipotransfer showed better fat integrity, fewer oil cysts, and reduced fibrosis. At week 10, graft retention rates in cell-assisted lipotransfer (50.9 ± 2.4 percent; p = 0.03) and exosome groups (56.4 ± 1.6 percent; p < 0.001) were significantly higher than in the saline group (40.7 ± 4.7 percent). Further investigations of macrophage infiltration, inflammatory factors, angiogenic factors, adipogenic factors, and extracellular matrix revealed that those exosomes promoted angiogenesis and up-regulated early inflammation, whereas during mid to late stages of fat grafting, they exerted a proadipogenic effect and also increased collagen synthesis level similarly to their source cells.

CONCLUSIONS

The adipose-derived stem cell-derived exosomes demonstrated effects comparable to those of their source cells in achieving improved graft retention by up-regulating early inflammation and augmenting angiogenesis. These features may enable exosomes to be an attractive cell-free alternative in therapeutic regenerative medicine.

Split Thickness Grafts Grow From Bottom Up in Large Skin Injuries

Autologous split thickness skin graft is necessary for the survival of patients with large burns and skin defects. It is not clear how a thin split thickness skin graft becomes remarkably thicker within a few weeks following transplantation. Here, we hypothesized that growth of split thickness graft should be from bottom up probably through conversion of immune cells into collagen producing skin cells. We tested this hypothesis in a preclinical porcine model by grafting split thickness meshed skin (0.508 mm thickness, meshed at 3:1 ratio) on full thickness wounds in pigs. New tissue formation was evaluated on days 10 and 20 postoperation through histological analysis and co-staining for immune cell markers (CD45) and type I collagen. The findings revealed that a split thickness graft grew from bottom up and reached to almost the same level as uninjured skin within 60 days postoperation. The result of immune-staining identified a large number of cells, which co-expressed immune cell marker (CD45) and collagen on day 10 postoperation. Interestingly, as the number of these cells reduced on day 20, most of these cells became positive for collagen production. In another set of experiments, we tested whether immune cells can convert to collagen producing cells in vitro. The results showed that mouse adherent immune cells started to express type 1 procollagen and α-smooth muscle actin when cultured in the presence of fibroblast conditioned media. In conclusion, the early thickening of split thickness graft is likely happening through a major contribution of infiltrated immune cells that convert into mainly collagen producing fibroblasts in large skin injuries.

Metabolism in Acute-On-Chronic Liver Failure: The Solution More than the Problem

Chronic inflammatory liver disease with an acute deterioration of liver function is named acute-on-chronic inflammation and could be regulated by the metabolic impairments related to the liver dysfunction. In this way, the experimental cholestasis model is excellent for studying metabolism in both types of inflammatory responses. Along the evolution of this model, the rats develop biliary fibrosis and an acute-on-chronic decompensation. The acute decompensation of the liver disease is associated with encephalopathy, ascites, acute renal failure, an acute phase response and a splanchnic increase of pro- and anti-inflammatory cytokines. This multiorgan inflammatory dysfunction is mainly associated with a splanchnic and systemic metabolic switch with dedifferentiation of the epithelial, endothelial and mesothelial splanchnic barriers. Furthermore, a splanchnic infiltration by mast cells occurs, which suggests that these cells could carry out a compensatory metabolic role, especially through the modulation of hepatic and extrahepatic mitochondrial-peroxisome crosstalk. For this reason, we propose the hypothesis that mastocytosis in the acute-on-chronic hepatic insufficiency could represent the development of a survival metabolic mechanisms that mitigates the noxious effect of the hepatic functional deficit. A better understanding the pathophysiological response of the mast cells in liver insufficiency and portal hypertension would help to find new pathways for decreasing the high morbidity and mortality rate of these patients.

Autograft microskin combined with adipose-derived stem cell enhances wound healing in a full-thickness skin defect mouse model

OBJECTIVE

Autograft microskin transplantation has been widely used as a skin graft therapy in full-thickness skin defect. However, skin grafting failure can lead to a pathological delay wound healing due to a poor vascularization bed. Considering the active role of adipose-derived stem cell (ADSC) in promoting angiogenesis, we intend to investigate the efficacy of autograft microskin combined with ADSC transplantation for facilitating wound healing in a full-thickness skin defect mouse model.

MATERIAL AND METHODS

An in vivo full-thickness skin defect mouse model was used to evaluate the contribution of transplantation microskin and ADSC in wound healing. The angiogenesis was detected by immunohistochemistry staining. In vitro paracrine signaling pathway was evaluated by protein array and Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway, and protein-protein interaction network analysis.

RESULTS

Co-transplantation of microskin and ADSC potentiated the wound healing with better epithelization, smaller scar thickness, and higher angiogenesis (CD31) in the subcutaneous layer. We found both EGF and VEGF cytokines were secreted by microskin in vitro. Additionally, secretome proteomic analysis in a co-culture system of microskin and ADSC revealed that ADSC could secrete a wide range of important molecules to form a reacting network with microskin, including VEGF, IL-6, EGF, uPAR, MCP-3, G-CSF, and Tie-2, which most likely supported the angiogenesis effect as observed.

CONCLUSION

Overall, we concluded that the use of ADSC partially modulates microskin function and enhances wound healing by promoting angiogenesis in a full-thickness skin defect mouse model.

Differentiated fibrocytes assume a functional mesenchymal phenotype with regenerative potential

Fibrocytes (FCs) are hematopoietic lineage cells that migrate to sites of injury, transition to a mesenchymal phenotype, and help to mediate wound repair. Despite their relevance to human fibrotic disorders, there are few data characterizing basic FC biology. Herein, using proteomic, bioenergetic, and bioengineering techniques, we conducted deep phenotypic characterization of differentiating and mature FCs. Differentiation was associated with metabolic reprogramming that favored oxidative phosphorylation. Mature FCs had distinct proteomes compared to classic mesenchymal cells, formed functional stromae that supported epithelial maturation during in vitro organotypic culture, and exhibited in vivo survival and self-tolerance as connective tissue isografts. In an in vitro scratch assay, FCs promoted fibroblast migration and wound closure by paracrine signaling via the chemokine CXCL8 (interleukin-8). These findings characterize important aspects of FC differentiation and show that, in addition to their role in wound healing, FCs hold potential as an easily isolated autologous cell source for regenerative medicine.

Role of Fibroblast Populations in Periodontal Wound Healing and Tissue Remodeling

After injury to periodontal tissues, a sequentially phased healing response is initiated that enables wound closure and partial restoration of tissue structure and function. Wound closure in periodontal tissues involves the tightly regulated coordination of resident cells in epithelial and connective tissue compartments. Multiple cell populations in these compartments synergize their metabolic activities to reestablish a mucosal seal that involves the underlying periodontal connective tissues and the attachment of these tissues to the tooth surface. The formation of an impermeable seal around the circumference of the tooth is of particular significance in oral health since colonization of tooth surfaces by pathogenic biofilms promotes inflammation, which can contribute to periodontal tissue degradation and tooth loss. The reformation of periodontal tissue structures in the healing response centrally involves fibroblasts, which synthesize and organize the collagen fibers that link alveolar bone and gingiva to the cementum covering the tooth root. The synthesis and remodeling of nascent collagen matrices are of fundamental importance for the reestablishment of a functional periodontium and are mediated by diverse, multi-functional fibroblast populations that reside within the connective tissues of gingiva and periodontal ligament. Notably, after gingival wounding, a fibroblast sub-type (myofibroblast) arises, which is centrally involved in collagen synthesis and fibrillar remodeling. While myofibroblasts are not usually seen in healthy, mature connective tissues, their formation is enhanced by wound-healing cytokines. The formation of myofibroblasts is also modulated by the stiffness of the extracellular matrix, which is mechanosensed by resident precursor cells in the gingival connective tissue microenvironment. Here, we consider the cellular origins and the factors that control the differentiation and matrix remodeling functions of periodontal fibroblasts. An improved understanding of the regulation and function of periodontal fibroblasts will be critical for the development of new therapies to optimize the restoration of periodontal structure and function after wounding.

IL-7 overexpression enhances therapeutic potential of rat bone marrow mesenchymal stem cells for diabetic wounds

This study was aimed to enhance the healing potential of rat bone marrow mesenchymal stem cells against chronic diabetic wounds through interleukin-7 (IL-7) transfection. IL-7 plays an important role in wound healing and acts as a survival factor in some cell types. This study involves isolation, propagation, and characterization of mesenchymal stem cells (MSCs) and their modification with IL-7 gene via retroviral transfection. Transfected MSCs were assessed for their effect on angiogenic genes by qPCR. Wound healing potential of transfected MSCs was analyzed by scratch assay in vitro and by transplanting these cells in rat diabetic wound models in vivo. Wound area was measured for a period of 15 days and subsequent histological analysis was performed. qPCR results showed increased expression of IL-7 gene (p ≤ 0.05) and also principal angiogenic genes, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), VEGF receptor 1 (FLT-1), and VEGF receptor 2 (FLK-1) (p ≤ 0.05). Neuropilin-1 (NRP-1) did not show any significant change. In vitro analysis of IL-7 MSCs showed intense cell-cell connections and tube formation as compared to the normal MSCs. Rate of wound closure was more (p ≤ 0.001) in case of diabetic group transplanted with IL-7 MSCs. Histological examination revealed enhanced vascular supply in skin tissues of diabetic animals transplanted with IL-7 transfected MSCs as compared to normal MSCs. Immunohistochemical results showed significantly higher expression of IL-7 (p ≤ 0.001) and α-smooth muscle actin(p ≤ 0.001) in the tissue sections of IL-7 transfected group as compared to normal MSCs and the diabetic control group; the latter indicates increase in the number of blood vessels. It is concluded from this study that IL-7 overexpression in MSCs can enhance the healing potential of MSCs and aid in wound closure in diabetic animals through the induction of angiogenic genes.

Migratory, metabolic and functional alterations of fibrocytes in type 2 diabetes

Fibrocytes are bloodborne mesenchymal progenitor cells that are recruited to injured tissue sites and contribute to the repair process by acquiring a myofibroblast-like phenotype and producing extracellular matrix components and growth factors. Treatment with normal fibrocytes or their exosomes restores the ability of genetically diabetic mice to heal skin wounds, suggesting the existence of dysfunctional alterations in diabetic fibrocytes. This study compared the migratory, metabolic and functional characteristics of fibrocytes from patients with type 2 diabetes (T2DPs) and healthy controls (HCs). It was found that the frequency of these cells was abnormally low in the peripheral blood of T2DPs. Diabetic fibrocytes showed reduced expression of the C-X-C motif and C-C motif chemokine receptors (CXCR)4, (CCR)5, and CCR7, and demonstrated reduced migration in response to their ligands (CXCL)12, (CCL)5, and CCL21. They exhibited increased expression of the receptor for advanced glycation end product, suppression of the alternative AGE receptor 1, increased intracellular concentrations of AGEs, decreased expression of sirtuin-1 and elevated oxidative stress. In short-term cultures, fibrocytes from T2DPs released larger amounts of proinflammatory cytokines than those from HCs. Unlike normal fibrocytes, diabetic fibrocytes did not exhibit increased expression of type I collagen and α-smooth muscle actin on stimulation with transforming growth factor (TGF)-β1 and this abnormal response was associated with downregulation of TGF-β1 type II receptor on the cell surface. Study findings uncover multiple migratory and functional alterations of diabetic fibrocytes that may contribute to explain why T2DPs experience impaired wound healing and chronic ulcers. © 2018 IUBMB Life, 70(11):1122-1132, 2018.

Extracellular vesicle-mimetic nanovesicles transport LncRNA-H19 as competing endogenous RNA for the treatment of diabetic wounds

Diabetic wounds, one of the most enervating complications of diabetes mellitus, affect millions of people worldwide annually. Vascular insufficiency, caused by hyperglycemia, is one of the primary causes and categories of diabetic impaired wound healing. Recently, long noncoding RNA (LncRNA)-H19, which is significantly decreased in diabetes and may be crucial in triggering angiogenesis, has attracted increasing interest. The possible relationship between the decrease of LncRNA-H19 and the impairment of angiogenesis in diabetes could involve impairment of the insulin-phosphatidylinositol 3-kinase (PI3K)-Akt pathway via the interdiction of LncRNA-H19. Thus, a therapeutic strategy utilizing LncRNA-H19 delivery is feasible. In this study, we investigated the possibility of using high-yield extracellular vesicle-mimetic nanovesicles (EMNVs) as an effective nano-drug delivery system for LncRNA, and studied the function of EMNVs with a high content of LncRNA-H19 (^H19EMNVs). The results, which were exciting, showed that ^H19EMNVs had a strong ability to neutralize the regeneration-inhibiting effect of hyperglycemia, and could remarkably accelerate the healing processes of chronic wounds. Our results suggest that bioengineered EMNVs can serve as a powerful instrument to effectively deliver LncRNA and will be an extremely promising multifunctional drug delivery system in the immediate future.

Sca-1+ cardiac fibroblasts promote development of heart failure

The causative effect of GM-CSF produced by cardiac fibroblasts to development of heart failure has not been shown. We identified the pathological GM-CSF-producing cardiac fibroblast subset and the specific deletion of IL-17A signaling to these cells attenuated cardiac inflammation and heart failure. We describe here the CD45^- CD31^- CD29⁺ mEF-SK4⁺ PDGFRα⁺ Sca-1⁺ periostin⁺ (Sca-1⁺ ) cardiac fibroblast subset as the main GM-CSF producer in both experimental autoimmune myocarditis and myocardial infarction mouse models. Specific ablation of IL-17A signaling to Sca-1⁺ periostin⁺ cardiac fibroblasts (Postn^Cre Il17ra^fl/fl ) protected mice from post-infarct heart failure and death. Moreover, Postn^Cre Il17ra^fl/fl mice had significantly fewer GM-CSF-producing Sca-1⁺ cardiac fibroblasts and inflammatory Ly6C^hi monocytes in the heart. Sca-1⁺ cardiac fibroblasts were not only potent GM-CSF producers, but also exhibited plasticity and switched their cytokine production profiles depending on local microenvironments. Moreover, we also found GM-CSF-positive cardiac fibroblasts in cardiac biopsy samples from heart failure patients of myocarditis or ischemic origin. Thus, this is the first identification of a pathological GM-CSF-producing cardiac fibroblast subset in human and mice hearts with myocarditis and ischemic cardiomyopathy. Sca-1⁺ cardiac fibroblasts direct the type of immune cells infiltrating the heart during cardiac inflammation and drive the development of heart failure.

The emerging role of fibrocytes in ocular disorders

The fibrocyte, which was first described in 1994, is a type of circulating mesenchymal progenitor cell in the peripheral blood. Fibrocytes play important roles in chronic inflammation, wound healing, tissue remodeling, and fibrosis. Emerging evidence indicates that fibrocytes are involved in a wide variety of ocular disorders associated with inflammation and fibrosis. In this review, we summarize recent advances regarding the general characteristic profile of fibrocytes, molecular mechanisms underlying the fibrocyte recruitment to target tissues, their differentiation into fibroblasts, and the potential role of fibrocytes in ocular disease. Given the critical role of fibrocytes in ocular disorders, fibrocytes may serve as a promising pharmaceutical target in the development of novel therapeutic strategies to treat ocular inflammation and fibrosis.

Should open excisions and sutured incisions be treated differently? A review and meta-analysis of animal wound models following low-level laser therapy

Although low-level laser therapy (LLLT) was discovered already in the 1960s of the twentieth century, it took almost 40 years to be widely used in clinical dermatology/surgery. It has been demonstrated that LLLT is able to increase collagen production/wound stiffness and/or improve wound contraction. In this review, we investigated whether open and sutured wounds should be treated with different LLLT parameters. A PubMed search was performed to identify controlled studies with LLLT applied to wounded animals (sutured incisions-tensile strength measurement and open excisions-area measurement). Final score random effects meta-analyses were conducted. Nineteen studies were included. The overall result of the tensile strength analysis (eight studies) was significantly in favor of LLLT (SMD = 1.06, 95% CI 0.66-1.46), and better results were seen with 30-79 mW/cm² infrared laser (SMD = 1.44, 95% CI 0.67-2.21) and 139-281 mW/cm² red laser (SMD = 1.52, 95% CI 0.54-2.49). The overall result of the wound contraction analysis (11 studies) was significantly in favor of LLLT (SMD = 0.99, 95% CI 0.38-1.59), and the best results were seen with 53-300 mW/cm² infrared laser (SMD = 1.18, 95% CI 0.41-1.94) and 25-90 mW/cm² red laser (SMD = 1.6, 95% CI 0.27-2.93). Whereas 1-15 mW/cm² red laser had a moderately positive effect on sutured wounds, 2-4 mW/cm² red laser did not accelerate healing of open wounds. LLLT appears effective in the treatment of sutured and open wounds. Statistical heterogeneity indicates that the tensile strength development of sutured wounds is more dependent on laser power density compared to the contraction rate of open wounds.

Supraspinatus tendon repair using anchors: a biomechanical evaluation in the rabbit

Background

Arthroscopic rotator cuff repairs are mostly secured with suture anchors and often supplemented by footprint decortication. The objectives of this study were to characterize the strength of bone–tendon healing following anchor repair and assess the effect of channeling the supraspinatus (SSP) humeral footprint 1 week ahead of reattachment surgery.

Methods

One hundred twelve rabbits underwent unilateral detachment of one SSP tendon and were randomly assigned to two groups: channeling the footprint at time of detachment and no channeling. One week later, reattachment was performed using an anchor. The repaired and contralateral shoulders were harvested at 0, 1, 2, or 4 weeks after repair and mechanically tested to failure. Outcome measures included load at failure, stiffness, and site of failure.

Results

Anchor fixation had a mean load at failure of 81 ± 32 N and a stiffness of 27 ± 9 N/mm immediately after repair compared to 166 ± 47 N and 66 ± 13 N/mm in the contralateral (both p < 0.05). Mechanical recovery of the reattached SSP tendon was achieved after 4 weeks (221 ± 73 N, 206 ± 59 N, and 198 ± 49 N in the channeling, no channeling, and contralateral groups, respectively, p > 0.05). The dominant site of failure shifted from the footprint at 0/1 week to bone avulsion/mid-substance tear at 4 weeks (p < 0.05). There were no differences in outcomes between the channeling and no channeling groups.

Conclusions

This study is the first of its kind to provide quantitative data on the mechanical properties of the enthesis following anchor repair in a rabbit model. Anchor repair led to rapid and complete restoration of SSP mechanical properties. Further evidence is needed before recommending channeling ahead of repair surgery.

The Role of Immune and Inflammatory Cells in Idiopathic Pulmonary Fibrosis

The contribution of the immune system to idiopathic pulmonary fibrosis (IPF) remains poorly understood. While most sources agree that IPF does not result from a primary immunopathogenic mechanism, evidence gleaned from animal modeling and human studies suggests that innate and adaptive immune processes can orchestrate existing fibrotic responses. This review will synthesize the available data regarding the complex role of professional immune cells in IPF. The role of innate immune populations such as monocytes, macrophages, myeloid suppressor cells, and innate lymphoid cells will be discussed, as will the activation of these cells via pathogen-associated molecular patterns derived from invading or commensural microbes, and danger-associated molecular patterns derived from injured cells and tissues. The contribution of adaptive immune responses driven by T-helper cells and B cells will be reviewed as well. Each form of immune activation will be discussed in the context of its relationship to environmental and genetic factors, disease outcomes, and potential therapies. We conclude with discussion of unanswered questions and opportunities for future study in this area.

Fibrocyte migration, differentiation and apoptosis during the corneal wound healing response to injury

The aim of this study was to determine whether bone marrow-derived fibrocytes migrate into the cornea after stromal scar-producing injury and differentiate into alpha-smooth muscle actin (αSMA) + myofibroblasts. Chimeric mice expressing green fluorescent protein (GFP) bone marrow cells had fibrosis (haze)-generating irregular phototherapeutic keratectomy (PTK). Multiplex immunohistochemistry (IHC) for GFP and fibrocyte markers (CD34, CD45, and vimentin) was used to detect fibrocyte infiltration into the corneal stroma and the development of GFP+ αSMA+ myofibroblasts. IHC for activated caspase-3, GFP and CD45 was used to detect fibrocyte and other hematopoietic cells undergoing apoptosis. Moderate haze developed in PTK-treated mouse corneas at 14 days after surgery and worsened, and persisted, at 21 days after surgery. GFP+ CD34+ CD45+ fibrocytes, likely in addition to other CD34+ and/or CD45+ hematopoietic and stem/progenitor cells, infiltrated the cornea and were present in the stroma in high numbers by one day after PTK. The fibrocytes and other bone marrow-derived cells progressively decreased at four days and seven days after surgery. At four days after PTK, 5% of the GFP+ cells expressed activated caspase-3. At 14 days after PTK, more than 50% of GFP+ CD45+ cells were also αSMA+ myofibroblasts. At 21 days after PTK, few GFP+ αSMA+ cells persisted in the stroma and more than 95% of those remaining expressed activated caspase-3, indicating they were undergoing apoptosis. GFP+ CD45+ SMA+ cells that developed from 4 to 21 days after irregular PTK were likely developed from fibrocytes. After irregular PTK in the strain of C57BL/6-C57/BL/6-Tg(UBC-GFP)30Scha/J chimeric mice, however, more than 95% of fibrocytes and other hematopoietic cells underwent apoptosis prior to the development of mature αSMA+ myofibroblasts. Most GFP+ CD45+ αSMA+ myofibroblasts that did develop subsequently underwent apoptosis-likely due to epithelial basement membrane regeneration and deprivation of epithelium-derived TGFβ requisite for myofibroblast survival.

Thymic stromal lymphopoietin contribution to the recruitment of circulating fibrocytes to the lung in a mouse model of chronic allergic asthma

Objective: Fibrocyte localization to the airways and thymic stromal lymphopoietin (TSLP) overexpression in the lung are features of severe asthma. The aim of this study was to determine whether TSLP contributes to fibrocyte trafficking and airway remodeling in a mouse model of allergic asthma. Methods: We established a chronic asthma animal model by administering house dust mite (HDM) extracts intranasally for up to 5 consecutive weeks. Mouse anti-TSLP monoclonal antibody (mAb) was given intraperitoneally starting the 4^th week. Fluorescence-labeled CD34/collagen I (Col I)-dual-positive fibrocytes were examined by confocal microscopy. The level of TGF-β1 in the bronchoalveolar lavage (BAL) fluid was determined by ELISA. Results: We found significantly increased levels of TSLP and TGF-β1 in the lung of the mice subjected to repeated allergen exposure, which was accompanied by increased number of fibrocytes in the sub-epithelial zone and the BAL fluid. However, blocking TSLP markedly decreased the production of TGF-β1, reduced the number of fibrocytes and subsequently prevented alterations of both airway and vascular structures. Conclusions: Our data suggested that TSLP might function in airway remodeling by promoting circulating fibrocyte recruitment to the lung in the mice subjected to chronic allergen exposure. These results provide a better rationale for targeting the interaction between TSLP and fibrocytes as a therapeutic approach for chronic allergic asthma.

Randomized clinical trial of autologous skin cell suspension for accelerating re-epithelialization of split-thickness donor sites

BACKGROUND

Split-thickness skin graft (STSG) is used frequently, but may result in complications at the donor site. Rapid healing of donor-site wounds is critical to relieving morbidity. This study investigated whether autologous skin cell suspension could improve healing of STSG donor-site wounds.

METHODS

Between September 2014 and February 2016, patients requiring STSGs were randomized to receive autologous skin cell suspension plus hydrocolloid dressings (experimental group) or hydrocolloid dressings alone (control group) for the donor site. The primary outcome was time to complete re-epithelialization. Secondary outcomes included pain and itching scores measured on a visual analogue scale, and adverse events. Patients were followed for 12 weeks to evaluate quality of healing. Analysis was by intention to treat.

RESULTS

Some 106 patients were included, 53 in each group. Median time to complete re-epithelialization was 9·0 (95 per cent c.i. 8·3 to 9·7) days in the experimental group, compared with 13·0 (12·4 to 13·6) days in the control group (P < 0·001). Overall postoperative pain and itching scores were similar in both groups. No between-group differences in treatment-related complications were observed. Both patients and observers were more satisfied with healing quality after autologous skin cell suspension had been used.

CONCLUSION

The use of autologous skin cell suspension with hydrocolloid dressings accelerated epithelialization and improved healing quality of the donor site compared with hydrocolloid dressings alone. Registration number: UMIN000015000 ( http://www.umin.ac.jp/ctr).

A primer on current progress in cardiac fibrosis

Cardiac fibrosis is a significant global health problem that is closely associated with multiple forms of cardiovascular disease, including myocardial infarction, dilated cardiomyopathy, and diabetes. Fibrosis increases myocardial wall stiffness due to excessive extracellular matrix deposition, causing impaired systolic and diastolic function, and facilitating arrhythmogenesis. As a result, patient morbidity and mortality are often dramatically elevated compared with those with cardiovascular disease but without overt fibrosis, demonstrating that fibrosis itself is both a pathologic response to existing disease and a significant risk factor for exacerbation of the underlying condition. The lack of any specific treatment for cardiac fibrosis in patients suffering from cardiovascular disease is a critical gap in our ability to care for these individuals. Here we provide an overview of the development of cardiac fibrosis, and discuss new research directions that have recently emerged and that may lead to the creation of novel treatments for patients with cardiovascular diseases. Such treatments would, ideally, complement existing therapy by specifically focusing on amelioration of fibrosis.

FOXO1 expression in keratinocytes promotes connective tissue healing

Wound healing is complex and highly orchestrated. It is well appreciated that leukocytes, particularly macrophages, are essential for inducing the formation of new connective tissue, which requires the generation of signals that stimulate mesenchymal stem cells (MSC), myofibroblasts and fibroblasts. A key role for keratinocytes in this complex process has yet to be established. To this end, we investigated possible involvement of keratinocytes in connective tissue healing. By lineage-specific deletion of the forkhead box-O 1 (FOXO1) transcription factor, we demonstrate for the first time that keratinocytes regulate proliferation of fibroblasts and MSCs, formation of myofibroblasts and production of collagen matrix in wound healing. This stimulation is mediated by a FOXO1 induced TGFβ1/CTGF axis. The results provide direct evidence that epithelial cells play a key role in stimulating connective tissue healing through a FOXO1-dependent mechanism. Thus, FOXO1 and keratinocytes may be an important therapeutic target where healing is deficient or compromised by a fibrotic outcome.

Circulating fibrocyte mobilization in negative pressure wound therapy

Non‐healing diabetic wounds are difficult to treat. They also create heavy financial burdens for both patients and society. Negative pressure wound therapy (NPWT) has been adopted to treat intractable wounds and has proved to be effective. However, the mechanisms that underlie the effects of this treatment are not entirely understood. Circulating fibrocytes are unique haematopoietic‐derived stem cells that have been reported to play a pivotal role in wound healing. Here, we have investigated the effect of NPWT on fibrocyte mobilization and the role of fibrocyte mobilization in the healing of diabetic wounds during NPWT. We show that the NPWT group exhibited 2.6‐fold to 12.1‐fold greater numbers of tail vein‐injected PKH‐26‐labelled fibrocytes in the diabetic wound sites compared with the control group. We also demonstrate that the full‐thickness skin wounds treated with NPWT exhibit significantly reduced mRNA and protein expression, blood vessel density and proliferating cells when exogenous fibrocyte mobilization is inhibited. We speculate that systemic mobilization of fibrocytes during NPWT may be a mechanism for healing intractable wounds in a diabetic rat model experiment and that enhancement of cell mobilization may represent a potential treatment idea for intractable wound healing across all fields of surgery.

Role of Circulating Fibrocytes in Cardiac Fibrosis

OBJECTIVE

It is revealed that circulating fibrocytes are elevated in patients/animals with cardiac fibrosis, and this review aims to provide an introduction to circulating fibrocytes and their role in cardiac fibrosis.

DATA SOURCES

This review is based on the data from 1994 to present obtained from PubMed. The search terms were "circulating fibrocytes " and "cardiac fibrosis ".

STUDY SELECTION

Articles and critical reviews, which are related to circulating fibrocytes and cardiac fibrosis, were selected.

RESULTS

Circulating fibrocytes, which are derived from hematopoietic stem cells, represent a subset of peripheral blood mononuclear cells exhibiting mixed morphological and molecular characteristics of hematopoietic and mesenchymal cells (CD34+/CD45+/collagen I+). They can produce extracellular matrix and many cytokines. It is shown that circulating fibrocytes participate in many fibrotic diseases, including cardiac fibrosis. Evidence accumulated in recent years shows that aging individuals and patients with hypertension, heart failure, coronary heart disease, and atrial fibrillation have more circulating fibrocytes in peripheral blood and/or heart tissue, and this elevation of circulating fibrocytes is correlated with the degree of fibrosis in the hearts.

CONCLUSIONS

Circulating fibrocytes are effector cells in cardiac fibrosis.