Clonal analysis of nestin– vimentin+ multipotent fibroblasts isolated from human dermis

A point-of-research decision in synovial tissue engineering: Mesenchymal stromal cells, tissue derived fibroblast or CTGF-mediated mesenchymal-to-fibroblast transition

Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent inflammatory joint diseases characterized by synovitis, cartilage, and bone destruction. Fibroblast-like synoviocytes (FLSs) of the synovial membrane are a decisive factor in arthritis, making them a target for future therapies. Developing novel strategies targeting FLSs requires advanced in vitro joint models that accurately replicate non-diseased joint tissue. This study aims to identify a cell source reflecting physiological synovial fibroblasts. Therefore, we newly compared the phenotype and metabolism of "healthy" knee-derived FLSs from patients with ligament injuries (trauma-FLSs) to mesenchymal stromal cells (MSCs), their native precursors. We differentiated MSCs into fibroblasts using connective tissue growth factor (CTGF) and compared selected protein and gene expression patterns to those obtained from trauma-FLSs and OA-FLSs. Based on these findings, we explored the potential of an MSC-derived synovial tissue model to simulate a chronic inflammatory response akin to that seen in arthritis. We have identified MSCs as a suitable cell source for synovial tissue engineering because, despite metabolic differences, they closely resemble human trauma-derived FLSs. CTGF-mediated differentiation of MSCs increased HAS2 expression, essential for hyaluronan synthesis. It showed protein expression patterns akin to OA-FLSs, including markers of ECM components and fibrosis, and enzymes leading to a shift in metabolism towards increased fatty acid oxidation. In general, cytokine stimulation of MSCs in a synovial tissue model induced pro-inflammatory and pro-angiogenic gene expression, hyperproliferation, and increased glucose consumption, reflecting cellular response in human arthritis. We conclude that MSCs can serve as a proxy to study physiological synovial processes and inflammatory responses. In addition, CTGF-mediated mesenchymal-to-fibroblast transition resembles OA-FLSs. Thus, we emphasize MSCs as a valuable cell source for tools in preclinical drug screening and their application in tissue engineering.

Phenolic Ligand-Metal Charge Transfer Induced Copper Nanozyme with Reactive Oxygen Species-Scavenging Ability for Chronic Wound Healing

Chronic wounds frequently arise as a complication in diabetic patients, and their management remains a significant clinical hurdle due to their nonhealing nature featured by heightened oxidative stress and impaired healing cells at the wound site. Herein, we present a 2D copper antioxidant nanozyme induced by phenolic ligand-metal charge transfer (LMCT) to eliminate reactive oxygen species (ROS) and facilitate the healing of chronic diabetic wounds. We found that polyphenol ligands coordinated on the Cu3(PO4)2 nanosheets led to a strong charge transfer at the interface and regulated the valence states of Cu. The obtained Cu nanozyme exhibited efficient scavenging ability toward different oxidative species and protected human cells from oxidative damage. The nanozyme enhanced the healing of diabetic wounds by promoting re-epithelialization, collagen deposition, angiogenesis, and immunoregulation. This work demonstrates the LMCT-induced ROS scavenging ability on a nanointerface, providing an alternative strategy of constructing metal-based nanozymes for the treatment of diabetic wounds as well as other diseases.

Current Trends, Advances, and Challenges of Tissue Engineering-Based Approaches of Tooth Regeneration: A Review of the Literature

INTRODUCTION

Tooth loss is a significant health issue. Currently, this situation is often treated with the use of synthetic materials such as implants and prostheses. However, these treatment modalities do not fully meet patients' biological and mechanical needs and have limited longevity. Regenerative medicine focuses on the restoration of patients' natural tissues via tissue engineering techniques instead of rehabilitating with artificial appliances. Therefore, a tissue-engineered tooth regeneration strategy seems like a promising option to treat tooth loss.

OBJECTIVE

This review aims to demonstrate recent advances in tooth regeneration strategies and discoveries about underlying mechanisms and pathways of tooth formation.

RESULTS AND DISCUSSION

Whole tooth regeneration, tooth root formation, and dentin-pulp organoid generation have been achieved by using different seed cells and various materials for scaffold production. Bioactive agents are critical elements for the induction of cells into odontoblast or ameloblast lineage. Some substantial pathways enrolled in tooth development have been figured out, helping researchers design their experiments more effectively and aligned with the natural process of tooth formation.

CONCLUSION

According to current knowledge, tooth regeneration is possible in case of proper selection of stem cells, appropriate design and manufacturing of a biocompatible scaffold, and meticulous application of bioactive agents for odontogenic induction. Understanding innate odontogenesis pathways play a crucial role in accurately planning regenerative therapeutic interventions in order to reproduce teeth.

Feline umbilical cord-derived mesenchymal stem cells: isolation, identification, and antioxidative stress role through NF-κB signaling pathway

At present, the differentiation potential and antioxidant activity of feline umbilical cord-derived mesenchymal stem cells (UC-MSCs) have not been clearly studied. In this study, feline UC-MSCs were isolated by tissue adhesion method, identified by flow cytometry detection of cell surface markers (CD44, CD90, CD34, and CD45), and induced differentiation toward osteogenesis and adipogenesis in vitro. Furthermore, the oxidative stress model was established with hydrogen peroxide (H₂O₂) (100 μM, 300 μM, 500 μM, 700 μM, and 900 μM). The antioxidant properties of feline UC-MSCs and feline fibroblasts were compared by morphological observation, ROS detection, cell viability via CCK-8 assay, as well as oxidative and antioxidative parameters via ELISA. The mRNA expression of genes related to NF-κB pathway was detected via quantitative real-time polymerase chain reaction, while the levels of NF-κB signaling cascade-related proteins were determined via Western Blot. The results showed that feline UC-MSCs highly expressed CD44 and CD90, while negative for CD34 and CD45 expression. Feline UC-MSCs cultured under osteogenic and adipogenic conditions showed good differentiation capacity. After being exposed to different concentrations of H₂O₂ for eight hours, feline UC-MSCs exhibited the significantly higher survival rate than feline fibroblasts. A certain concentration of H₂O₂ could up-regulate the activities of SOD2 and GSH-Px in feline UC-MSCs. The expression levels of p50, MnSOD, and FHC mRNA in feline UC-MSCs stimulated by 300 μM and 500 μM H₂O₂ significantly increased compared with the control group. Furthermore, it was observed that 500 μM H₂O₂ significantly enhanced the protein levels of p-IκB, IκB, p-p50, p50, MnSOD, and FHC, which could be reversed by BAY 11-7,082, a NF-κB signaling pathway inhibitor. In conclusion, it was confirmed that feline UC-MSCs, with good osteogenesis and adipogenesis abilities, had better antioxidant property which might be related to NF-κB signaling pathway. This study lays a foundation for the further application of feline UC-MSCs in treating the various inflammatory and oxidative injury diseases of pets.

Preparation of therapy-grade extracellular vesicles from adipose tissue to promote diabetic wound healing

Background: Treatment of diabetic wounds is a major challenge in clinical practice. Extracellular vesicles (EVs) from adipose-derived stem cells have shown effectiveness in diabetic wound models. However, obtaining ADSC-EVs requires culturing vast numbers of cells, which is hampered by the need for expensive equipment and reagents, extended time cost, and complicated procedures before commercialization. Therefore, methods to extract EVs from discarded tissue need to be developed, for immediate application during surgery. For this reason, mechanical, collagenase-digestive, and constant in-vitro-collective methods were designed and compared for preparing therapy-grade EVs directly from adipose tissue. Methods: Characteristics and quantities of EVs were detected by transmission electron microscopy, nanoparticle tracking analysis, and Western blotting firstly. To investigate the biological effects of EVs on diabetic wound healing, angiogenesis, proliferation, migration, and inflammation-regulation assays were then evaluated in vitro, along with a diabetic wound healing mouse model in vivo. To further explore the potential therapeutic mechanism of EVs, miRNA expression profile of EVs were also identified and analyzed. Results: The adipose tissue derived EVs (AT-EVs) were showed to qualify ISEV identification by nanoparticle tracking analysis and Western blotting and the AT-EVs yield from three methods was equal. EVs also showed promoting effects on biological processes related to diabetic wound healing, which depend on fibroblasts, keratinocytes, endothelial cells, and macrophages both in vitro and in vivo. We also observed enrichment of overlapping or unique miRNAs originate from different types of AT-EVs associated with diabetic wound healing for further investigation. Conclusion: After comparative analyses, a mechanical method was proposed for preparing immediate clinical applicable EVs from adipose tissue that would result in reduced preparation time and lower cost, which could have promising application potential in treating diabetic wounds.

Production and Biological Effects of Extracellular Vesicles from Adipose-Derived Stem Cells Were Markedly Increased by Low-Intensity Ultrasound Stimulation for Promoting Diabetic Wound Healing

Diabetic wound treatment has posed a significant challenge in clinical practice. As a kind of cell-derived nanoparticles, extracellular vesicles produced by adipose-derived stem cells (ADSC-EVs) have been reported to be potential agents for diabetic wound treatment. However, ADSC-EV yield is insufficient to meet the demands of clinical therapy. In this study, a novel method involving the use of low-intensity ultrasound stimulation on ADSCs is developed to promote EV secretion for clinical use. A proper low-intensity ultrasound stimulation parameter which significantly increases ADSC-EV quantity has been found. In addition, EVs secreted by ADSCs following low-intensity ultrasound stimulation (US-EVs) are enriched in wound healing-related miRNAs. Moreover, US-EVs promote the biological functions of fibroblasts, keratinocytes, and endothelial cells in vitro, and promote diabetic wound healing in db/db mice in vivo through re-epithelialization, collagen production, cell proliferation, keratinocyte differentiation and migration, and angiogenesis. This study proposes low-intensity ultrasound stimulation as a new method for promoting significant EV secretion by ADSCs and for improving the diabetic wound-healing potential of EVs, which will meet the clinical needs for these nanoparticles. The production of extracellular vesicles of adipose-derived stem cells is obviously promoted by a low-intensity ultrasound stimulation method, and the biological effects of promoting diabetic wound healing were markedly increased in vitro and in vivo.

Melanin accumulation in dermal stem cells deteriorates their exosome-mediated skin basement membrane construction in solar lentigo

Solar lentigo (SL) is a hyperpigmented macule that occurs in sun-exposed areas and is characterized by the accumulation of melanin pigment in the epidermis. On the contrary, melanin-incorporated macrophages have also been identified in the dermis, which is thought to be caused by melanin transfer due to disruption of the basement membrane, but the detailed mechanism remains unclear. In this study, we analysed SL lesions by pathological methods and examined the mechanism of melanin accumulation in the dermis using cultured skin models in vitro. First, we observed a significant decrease in type IV collagen (COL4), a major component of the basement membrane, in SL lesions. The basement membrane is known to be formed by the interaction of keratinocytes and dermal cells. Therefore, we constructed skin models containing fibroblasts or dermal stem cells and examined their effects on basement membrane formation. The results showed a markedly enhanced production of COL4 mediated by dermal stem cell-derived exosomes. The analysis of melanin localization in the SL dermis revealed that CD163-positive macrophages and CD271-positive dermal stem cells both took up melanin pigment. Exosomes of dermal stem cells incorporating melanosomes were less effective in promoting COL4 expression. These findings suggest that while the promotion of COL4 production in keratinocytes by dermal stem cell-derived exosomes is important for maintaining basement membrane homeostasis, this mechanism is disrupted in SL lesions, leading to chronic melanin accumulation in the dermis.

Discovery and characterization of heterogeneous and multipotent fibroblast populations isolated from excised cleft lip tissue

Background

Regularly discarded lip tissue obtained from corrective surgeries to close the cleft lip represents an easily accessible and rich source for the isolation of primary fibroblasts. Primary fibroblasts have been described to show compelling similarities to mesenchymal stem cells (MSCs). Hence, cleft lip and palate (CLP) lip-derived fibroblasts could be thought as an intriguing cell source for personalized regenerative therapies in CLP-affected patients.

Methods

Initially, we thoroughly characterized the fibroblastic nature of the lip-derived mesenchymal outgrowths by molecular and functional assays. Next, we compared their phenotype and genotype to that of bone marrow-mesenchymal stem cells (BM-MSCs) and of human lung-derived fibroblasts WI38, by assessing their morphology, surface marker expression, trilineage differentiation potential, colony-forming (CFU) capacity, and immunomodulation property. Finally, to better decipher the heterogeneity of our CLP cultures, we performed a single cell clonal analysis and tested expanded clones for surface marker expression, as well as osteogenic and CFU potential.

Results

We identified intriguingly similar phenotypic and genotypic properties between CLP lip fibroblasts and BM-MSCs, which makes them distinct from WI38. Furthermore, our own data in combination with the complex anatomy of the lip tissue indicated heterogeneity in our CLP cultures. Using a clonal analysis, we discovered single cell-derived clones with increased levels of the MSC markers CD106 and CD146 and clones with variabilities in their commitment to differentiate into bone-forming cells and in their potential to form single cell-derived colonies. However, we were not able to gain clones possessing superior MSC-like capacities when compared to the heterogeneous parental CLP population. Additionally, all clones could still generate contractile forces and retained robust levels of the fibroblast specific marker FSP1, which was not detectable in BM-MSCs.

Conclusions

Our results suggest that we isolate heterogeneous populations of fibroblasts from discarded CLP lip tissue, which show a prominently multipotent character in their entirety avoiding the need for elaborate subpopulation selections in vitro. These findings suggest that CLP lip fibroblasts might be a novel potential cell source for personalized regenerative medicine of clinical benefit for CLP patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03154-x.

Chemically-induced osteogenic cells for bone tissue engineering and disease modeling

Cell reprogramming can satisfy the demands of obtaining specific cell types for applications such as tissue regeneration and disease modeling. Here we report the reprogramming of human fibroblasts to produce chemically-induced osteogenic cells (ciOG), and explore the potential uses of ciOG in bone repair and disease treatment. A chemical cocktail of RepSox, forskolin, and phenamil was used for osteogenic induction of fibroblasts by activation of RUNX2 expression. Following a maturation, the cells differentiated toward an osteoblast phenotype that produced mineralized nodules. Bulk and single-cell RNA sequencing identified a distinct ciOG population. ciOG formed mineralized tissue in an ectopic site of immunodeficiency mice, unlike the original fibroblasts. Osteogenic reprogramming was modulated under engineered culture substrates. When generated on a nanofiber substrate ciOG accelerated bone matrix formation in a calvarial defect, indicating that the engineered biomaterial promotes the osteogenic capacity of ciOG in vivo. Furthermore, the ciOG platform recapitulated the genetic bone diseases Proteus syndrome and osteogenesis imperfecta, allowing candidate drug testing. The reprogramming of human fibroblasts into osteogenic cells with a chemical cocktail thus provides a source of specialized cells for use in bone tissue engineering and disease modeling.

Generating Human Induced Pluripotent Stem Cell Via Low-Dose Polyethylenimine-Mediated Transfection: An Optimized Protocol

Human dermal fibroblasts (HDFs) can be reprogrammed through different strategies to generate human induced pluripotent stem cells (hiPSCs). However, most of these strategies require high-cost materials and specific equipment not readily accessible in most laboratories. Hence, liposomal and virus-based techniques can replace with polyethylenimine (PEI)-mediated transfection to overcome these challenges. However, few researchers have addressed the PEI's ability to transfect HDFs. This study used PEI reagent to transfer oriP/EBNA1-based vector into HDFs to produce hiPSC lines. We first described conditions allowing the efficient transfection of HDFs with low cytotoxicity and without specific types of equipment and optimized several parameters relevant to the transfection procedure. We then monitored the effect of different N/P ratios on transfection efficiency and cytotoxicity using flow cytometry and fluorescent microscopy. By the results, we found that transfection efficiency was greatly affected by plasmid DNA concentration, PEI concentration, order of combining reagents, serum presence in polyplexes, and the duration of serum starvations. Moreover, using the optimized condition, we found that the N/P ratio of 3 achieved the highest percentage of HDFs positive for green fluorescent protein plasmid (∼40%) with minimal cell toxicity. We finally generated hiPSCs using the optimized protocol and oriP/EBNA1-based vectors. We confirmed hiPSC formation by characterizing tests: alkaline phosphatase staining, immunocytochemistry assay, real-time PCR analysis, in vitro differentiation into three germ layers, and karyotyping test. In conclusion, our results indicated that 25 kDa branched PEI could efficiently transfect HDFs toward generating hiPSCs via a simple, cost-effective, and optimized condition.

The Downregulated Lipo-Related Gene Expression Pattern in Keloid Indicates Fat Graft Is a Potential Clinical Option for Keloid

Background

Keloids are a common complication of wounds, often manifesting with continuous hyperplasia and aggressive growth. Keloids also have a high recurrence rate and are largely resistant to treatment, making them clinically incurable, highlighting the need to translate basic research into clinical practice.

Materials and Methods

We used GSE158395 and GSE92566 as discovery datasets to identify specific enriched hub genes and lncRNAs associated with keloid development and progression. This data was then used to identify the competing endogenous RNAs (ceRNAs) in these pathways by using a bidirectional selection method. Then, all hub genes and lncRNAs in ceRNAs were validated using GSE90051, GSE178562, and GSE175866, which describe the transcriptional profiles of keloid tissues, fibroblasts from pathological scars, and keloid fibroblast subpopulations, respectively. The keloid tissues were measured with qPCR.

Results

Both fat-associated biological processes and fat cell differentiation were enriched in the downregulated gene set. Further evaluation revealed that all 11 hub genes were lipo-related, and most of these were differentially expressed in all three validation datasets. We then identified a clear ceRNA network within the data comprising six hub genes and four lncRNAs. Evaluations of the validation datasets confirmed that all six of these hub genes and two of the four lncRNAs were downregulated in keloid tissues; two hub genes and one lncRNA were downregulated in fibroblasts from pathological scars; and five hub genes and one lncRNA were significantly downregulated in mesenchymal subpopulation. Three genes had statistical difference and eight genes showed downregulated trend through qPCR of the keloid tissue.

Conclusion

Our results suggest that keloid development relies on the downregulation of lipo-related genes and pre-adipocytes in diseased tissues and may be one of the key mechanisms underlying fat grafting-mediated treatment of pathological scarring.

Single-Cell Transcriptome Integration Analysis Reveals the Correlation Between Mesenchymal Stromal Cells and Fibroblasts

Background: Mesenchymal stromal cells (MSCs) and fibroblasts show similar morphology, surface marker expression, and proliferation, differentiation, and immunomodulatory capacities. These similarities not only blur their cell identities but also limit their application. Methods: We performed single-cell transcriptome sequencing of the human umbilical cord and foreskin MSCs (HuMSCs and FSMSCs) and extracted the single-cell transcriptome data of the bone marrow and adipose MSCs (BMSCs and ADMSCs) from the Gene Expression Omnibus (GEO) database. Then, we performed quality control, batch effect correction, integration, and clustering analysis of the integrated single-cell transcriptome data from the HuMSCs, FMSCs, BMSCs, and ADMSCs. The cell subsets were annotated based on the surface marker phenotypes for the MSCs (CD105 ⁺ , CD90 ⁺, CD73 ⁺, CD45 ^-, CD34 ^-, CD19 ^-, HLA-DRA ^-, and CD11b ^-), fibroblasts (VIM ⁺, PECAM1 ^-, CD34 ^-, CD45 ^-, EPCAM ^-, and MYH11 ^-), and pericytes (CD146 ⁺, PDGFRB ⁺, PECAM1 ^-, CD34 ^-, and CD45 ^-). The expression levels of common fibroblast markers (ACTA2, FAP, PDGFRA, PDGFRB, S100A4, FN1, COL1A1, POSTN, DCN, COL1A2, FBLN2, COL1A2, DES, and CDH11) were also analyzed in all cell subsets. Finally, the gene expression profiles, differentiation status, and the enrichment status of various gene sets and regulons were compared between the cell subsets. Results: We demonstrated 15 distinct cell subsets in the integrated single-cell transcriptome sequencing data. Surface marker annotation demonstrated the MSC phenotype in 12 of the 15 cell subsets. C10 and C14 subsets demonstrated both the MSC and pericyte phenotypes. All 15 cell subsets demonstrated the fibroblast phenotype. C8, C12, and C13 subsets exclusively demonstrated the fibroblast phenotype. We identified 3,275 differentially expressed genes, 305 enriched gene sets, and 34 enriched regulons between the 15 cell subsets. The cell subsets that exclusively demonstrated the fibroblast phenotype represented less primitive and more differentiated cell types. Conclusion: Cell subsets with the MSC phenotype also demonstrated the fibroblast phenotype, but cell subsets with the fibroblast phenotype did not necessarily demonstrate the MSC phenotype, suggesting that MSCs represented a subclass of fibroblasts. We also demonstrated that the MSCs and fibroblasts represented highly heterogeneous populations with distinct cell subsets, which could be identified based on the differentially enriched gene sets and regulons that specify proliferating, differentiating, metabolic, and/or immunomodulatory functions.

Maintenance of Chronological Aging Features in Culture of Normal Human Dermal Fibroblasts from Old Donors

Chronological aging is defined as a time-dependent decline of tissue homeostasis which severely impacts skin. Understanding the mechanisms of skin aging is an active research area limited by the lack of relevant in vitro models. Being a component of aging, replicative or stress-induced senescence is repeatedly used to mimic skin aging in vitro, thus presenting only a partial view of the complexity of aging. Herein, we aimed to clarify whether primary normal human dermal fibroblasts retained age-related characteristics when cultured in 2D monolayer, and could be used as a relevant model for aging research. We compared three groups of fibroblasts isolated from different aged donors. We observed strongly decreased population doubling capacities, a reduced clonogenic ability, an impairment in extracellular matrix production together with modifications of respiratory metabolism with an increase in age. These disruptions were particularly marked when comparing fibroblasts isolated from old individuals (over 70 years old) to those isolated from young individuals (18–37 years old), while cells from middle-aged donors exhibited an intermediate profile. These alterations of cell features can be related to the signs of dermis aging, thus showing that cultured primary cells indeed retain some characteristics of the original tissue from which they were extracted.

The Identification of Marker Genes for Predicting the Osteogenic Differentiation Potential of Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) have the potential to differentiate into a variety of mature cell types and are a promising source of regenerative medicine. The success of regenerative medicine using MSCs strongly depends on their differentiation potential. In this study, we sought to identify marker genes for predicting the osteogenic differentiation potential by comparing ilium MSC and fibroblast samples. We measured the mRNA levels of 95 candidate genes in nine ilium MSC and four fibroblast samples before osteogenic induction, and compared them with alkaline phosphatase (ALP) activity as a marker of osteogenic differentiation after induction. We identified 17 genes whose mRNA expression levels positively correlated with ALP activity. The chondrogenic and adipogenic differentiation potentials of jaw MSCs are much lower than those of ilium MSCs, although the osteogenic differentiation potential of jaw MSCs is comparable with that of ilium MSCs. To select markers suitable for predicting the osteogenic differentiation potential, we compared the mRNA levels of the 17 genes in ilium MSCs with those in jaw MSCs. The levels of 7 out of the 17 genes were not substantially different between the jaw and ilium MSCs, while the remaining 10 genes were expressed at significantly lower levels in jaw MSCs than in ilium MSCs. The mRNA levels of the seven similarly expressed genes were also compared with those in fibroblasts, which have little or no osteogenic differentiation potential. Among the seven genes, the mRNA levels of IGF1 and SRGN in all MSCs examined were higher than those in any of the fibroblasts. These results suggest that measuring the mRNA levels of IGF1 and SRGN before osteogenic induction will provide useful information for selecting competent MSCs for regenerative medicine, although the effectiveness of the markers is needed to be confirmed using a large number of MSCs, which have various levels of osteogenic differentiation potential.

Multifunctional Magnesium Organic Framework-Based Microneedle Patch for Accelerating Diabetic Wound Healing

Diabetic wound healing is one of the major challenges in the biomedical fields. The conventional single drug treatments have unsatisfactory efficacy, and the drug delivery effectiveness is restricted by the penetration depth. Herein, we develop a magnesium organic framework-based microneedle patch (denoted as MN-MOF-GO-Ag) that can realize transdermal delivery and combination therapy for diabetic wound healing. Multifunctional magnesium organic frameworks (Mg-MOFs) are mixed with poly(γ-glutamic acid) (γ-PGA) hydrogel and loaded into the tips of MN-MOF-GO-Ag, which slowly releases Mg²⁺ and gallic acid in the deep layer of the dermis. The released Mg²⁺ induces cell migration and endothelial tubulogenesis, while gallic acid, a reactive oxygen species-scavenger, promotes antioxidation. Besides, the backing layer of MN-MOF-GO-Ag is made of γ-PGA hydrogel and graphene oxide-silver nanocomposites (GO-Ag) which further enables excellent antibacterial effects for accelerating wound healing. The therapeutic effects of MN-MOF-GO-Ag on wound healing are demonstrated with the full-thickness cutaneous wounds of a diabetic mouse model. The significant improvement of wound healing is achieved for mice treated with MN-MOF-GO-Ag.

Anti-aging effects of fetal dermal mesenchymal stem cells in a D-galactose-induced aging model of adult dermal fibroblasts

The main characteristic of skin aging is the change in the composition of the dermis, mainly resulting from fibroblast senescence. Mesenchymal stem cells derived from fetal dermis are defined as fetal dermal mesenchymal stem cells; they reportedly exert wound healing effects on the skin and regulate keloid fibroblast proliferation. D-Galactose is widely used in animal aging models. In this study, we confirmed that D-galactose inhibits adult dermal fibroblast proliferation, and the inhibitory effect gradually increased with increasing concentration. Finally, we chose a concentration of 40 g/L D-galactose to induce adult dermal fibroblast senescence. D-Galactose increased the intensity of senescence-associated β-galactosidase staining and the levels of reactive oxygen species in adult dermal fibroblasts. Furthermore, D-galactose increased the mRNA expression of p16, p21, and p53. The fetal dermal mesenchymal stem cell-conditioned medium improved the above-mentioned effects. Overall, fetal dermal mesenchymal stem cells exerted anti-aging effects against adult dermal fibroblasts induced by D-galactose via paracrine functions.

Comparative Analysis of Human Adipose-Derived Stromal/Stem Cells and Dermal Fibroblasts

Dermal fibroblasts (DFs) share several qualities with mesenchymal stem cell/multipotent stromal cells (MSCs) derived from various tissues, including adipose-derived stromal/stem cells (ASCs). ASCs and DFs are morphologically comparable and both cell types can be culture expanded through the utilization of their plastic-adherence properties. Despite these similar characteristics, numerous studies indicate that ASC and DF display distinct therapeutic benefits in clinical applications. To more accurately distinguish between these cell types, human DFs and ASCs isolated from three individual donors were analyzed for multipotency and cell surface marker expressions. The detection of cell surface markers, CD29, CD34, CD44, CD73, CD90, and CD105, were used for phenotypic characterization of the DFs and ASCs. Furthermore, both cell types underwent lineage differentiation based on histochemical staining and the expression of adipogenic related genes, CCAAT/Enhancer-Binding Protein alpha (CEBPα), Peroxisome proliferator-activated receptor gamma (PPARγ), UCP1, Leptin (LEP), and Adiponectin (ADIPOQ); and osteogenic related genes, Runt related transcription factor 2 (Runx2), Alkaline phosphatase (ALPL), Osteocalcin (OCN), and Osteopontin (OPN). Evidence provided by this study demonstrates similarities between donor-matched ASC and DF with respect to morphology, surface marker expression, differentiation potential, and gene expression, although appearance of enhanced adipogenesis in the ASC based solely on spectrophotometric analyses with no significant difference in real-time polymerase chain reaction detection of adipogenic biomarkers. Thus, there is substantial overlap between the ASC and DF phenotypes based on biochemical and differentiation metrics.

CD39+ Fibroblasts Enhance Myofibroblast Activation by Promoting IL-11 Secretion in Hypertrophic Scars

Fibroblasts (Fbs) are critical to hypertrophic scar (HTS) formation and were recently shown to be highly heterogeneous. However, Fb heterogeneity in HTSs has not been fully elucidated. In this study, we observed an increased fraction of CD39⁺ Fbs in HTS after screening four Fb subtypes (CD26⁺, CD36⁺, FAP⁺, and CD39⁺). CD39⁺ Fbs, enriched in the upper dermis, were positively correlated with scar severity. The transcriptional analysis of CD39⁺ and CD39^- Fbs sorted from HTS revealed that IL-11 was more highly expressed in CD39⁺ Fbs. We then showed that IL-11 was upregulated in HTSs and that its expression was induced by TGFβ1 in vitro. TGFβ1 also stimulated the expression of CD39 at the transcriptional and protein levels, mediating the maintenance of the CD39⁺ phenotype. Furthermore, IL-11 facilitated myofibroblast activation and extracellular matrix production in both CD39⁺ and CD39^- Fbs. Interestingly, CD39⁺ Fbs secreted more IL-11 on TGFβ1 treatment and were less responsive to IL-11 than CD39^- Fbs. Notably, a CD39 inhibitor effectively reduced stretch-induced scar formation and attenuated bleomycin-induced skin fibrosis, suggesting an antiscarring approach by targeting CD39⁺ Fbs.

Cellular heterogeneity and microenvironmental control of skin cancer

Healthy tissues harbour a surprisingly high number of cells that carry well-known cancer-causing mutations without impacting their physiological function. In recent years, strong evidence accumulated that the immediate environment of mutant cells profoundly impact their prospect of malignant progression. In this review, focusing on the skin, we investigate potential key mechanisms that ensure tissue homeostasis despite the presence of mutant cells, as well as critical factors that may nudge the balance from homeostasis to tumour formation. Functional in vivo studies and single-cell transcriptome analyses have revealed a tremendous cellular heterogeneity and plasticity within epidermal (stem) cells and their respective niches, revealing for example wild-type epithelial cells, fibroblasts or immune-cell subsets as critical in preventing cancer formation and malignant progression. It's the same cells, however, that can drive carcinogenesis. Therefore, understanding the abundance and molecular variation of cell types in health and disease, and how they interact and modulate the local signalling environment will thus be key for new therapeutic avenues in our battle against cancer.

Adenosine Diphosphate Improves Wound Healing in Diabetic Mice Through P2Y12 Receptor Activation

Chronic wounds are a public health problem worldwide, especially those related to diabetes. Besides being an enormous burden to patients, it challenges wound care professionals and causes a great financial cost to health system. Considering the absence of effective treatments for chronic wounds, our aim was to better understand the pathophysiology of tissue repair in diabetes in order to find alternative strategies to accelerate wound healing. Nucleotides have been described as extracellular signaling molecules in different inflammatory processes, including tissue repair. Adenosine-5'-diphosphate (ADP) plays important roles in vascular and cellular response and is immediately released after tissue injury, mainly from platelets. However, despite the well described effect on platelet aggregation during inflammation and injury, little is known about the role of ADP on the multiple steps of tissue repair, particularly in skin wounds. Therefore, we used the full-thickness excisional wound model to evaluate the effect of local ADP application in wounds of diabetic mice. ADP accelerated cutaneous wound healing, improved new tissue formation, and increased both collagen deposition and transforming growth factor-β (TGF-β) production in the wound. These effects were mediated by P2Y12 receptor activation since they were inhibited by Clopidogrel (Clop) treatment, a P2Y12 receptor antagonist. Furthermore, P2Y1 receptor antagonist also blocked ADP-induced wound closure until day 7, suggesting its involvement early in repair process. Interestingly, ADP treatment increased the expression of P2Y12 and P2Y1 receptors in the wound. In parallel, ADP reduced reactive oxygen species (ROS) formation and tumor necrosis factor-α (TNF-α) levels, while increased IL-13 levels in the skin. Also, ADP increased the counts of neutrophils, eosinophils, mast cells, and gamma delta (γδ) T cells (Vγ4+ and Vγ5+ cells subtypes of γδ+ T cells), although reduced regulatory T (Tregs) cells in the lesion. In accordance, ADP increased fibroblast proliferation and migration, myofibroblast differentiation, and keratinocyte proliferation. In conclusion, we provide strong evidence that ADP acts as a pro-resolution mediator in diabetes-associated skin wounds and is a promising intervention target for this worldwide problem.

Human adipose-derived stromal/stem cells are distinct from dermal fibroblasts as evaluated by biological characterization and RNA sequencing

Human adipose-derived stromal/stem cells (ASC) have immunomodulatory properties and the potential to differentiate into several cell lines, important for application in regenerative medicine. However, the contamination with dermal fibroblasts (FIB) can impair the beneficial effects of ASC in cell therapy. It is then essential to develop new strategies that contribute to the distinction between these two cell types. In this study, we performed functional assays, high-throughput RNA sequencing (RNA-Seq) and quantitative PCR (qPCR) to find new markers that can distinguish ASC and FIB. We showed that ASC have adipogenic and osteogenic differentiation capacity and alkaline phosphatase activity, not observed in FIB. Gene expression variation analysis identified more than 2000 differentially expressed genes (DEG) between these two cell types. We validated 16 genes present in the list of DEG, including the alkaline phosphatase gene (ALPL). In conclusion, we showed that ASC and FIB have distinct biological properties as demonstrated by alkaline phosphatase activity and differentiation capacity, besides having different gene expression profiles. SIGNIFICANCE OF THE STUDY: Although many differences between stromal stem cells derived from human adipose tissue (ASC) and human dermal fibroblasts (FIB) are described, it is still difficult to find specific markers to differentiate them. This problem can interfere with the therapeutic use of ASC. This work aimed to find new markers to differentiate these two cell populations. Our findings suggest that these cells can be distinguished by biological and molecular characteristics, such as adipogenic and osteogenic differentiation, alkaline phosphatase activity and differential gene expression profiles. The DEG were related to the regulation of the cell cycle, development process, structural organization of the cell and synthesis of the extracellular matrix. This study helps to find new cellular markers to distinguish the two populations and to better understand the properties of these cells, which can improve cell therapy.

Comparison of similar cells: Mesenchymal stromal cells and fibroblasts

Almost from all organs, both mesenchymal stromal cells and fibroblasts can be isolated. Mesenchymal stromal cells (MSCs) are the most preferred cellular therapeutic agents with the regenerative potential, and fibroblasts are one of the most abundant cell types with the ability to maintain homeostasis. Because of the promising properties of MSCs, they have been well studied and their differentiation potentials, immunomodulatory potentials, gene expression profiles are identified. It has been observed that fibroblasts and mesenchymal stromal cells have similar morphology, gene expression patterns, surface markers, proliferation, differentiation, and immunomodulatory capacities. Thus, it is hard to distinguish these two cell types. Epigenetic signatures, i.e., methylation patterns of cells, are the only usable promising difference between them. Such significant similarities show that these two cells may be related to each other.

Circular RNA expression profiles significantly altered in UVA-irradiated human dermal fibroblasts

Circular RNAs (circRNAs) have been previously implicated in number of diseases. However, the roles of circRNAs in photoaging remain elusive. In the present study, to understand if photoaging influences the levels of circRNA expression, the expression of circRNAs in ultraviolet A (UVA)-irradiated human dermal fibroblasts were profiled. A total of 128 circRNAs were identified to be differentially expressed (fold change >1.5; P<0.05) after UVA exposure, including 39 upregulated and 89 downregulated circRNAs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes biological pathway analyses indicated that the differentially expressed circRNAs were associated with extracellular matrix organization and metabolism. The present study revealed an altered circRNA expression pattern in human dermal fibroblasts following UVA-irradiation. These results provide not only a basis for in-depth study of the mechanism of skin photoaging but also a new possibility for the prevention and treatment of photoaging and associated skin diseases.

Mesenchymal stem cell markers in periodontal tissues and periapical lesions

INTRODUCTION

Mesenchymal stem cells (MSCs) are characterized by the potential to differentiate into multiple cell lineages, high proliferation rates, and self-renewal capacity, in addition to the ability to maintain their undifferentiated state. These cells have been identified in physiological oral tissues such as pulp tissue, dental follicle, apical papilla and periodontal ligament, as well as in pathological situations such as chronic periapical lesions (CPLs). The criteria used for the identification of MSCs include the positive expression of specific surface antigens, with CD73, CD90, CD105, CD44, CD146, STRO-1, CD166, NANOG and OCT4 being the most specific for these cells.

AIM

The aim of this review was to explore the literature on markers able to identify MSCs as well as the presence of these cells in the healthy periodontal ligament and CPLs, highlighting their role in regenerative medicine and implications in the progression of these lesions.

METHODS

Narrative literature review searching the PubMed and Medline databases. Articles published in English between 1974 and 2020 were retrieved.

CONCLUSION

The included studies confirmed the presence of MSCs in the healthy periodontal ligament and in CPLs. Several surface markers are used for the characterization of these cells which, although not specific, are effective in cell recognition. Mesenchymal stem cells participate in tissue repair, exerting anti- inflammatory, immunosuppressive and proangiogenic effects, and are therefore involved in the progression and attenuation of CPLs or even in the persistence of these lesions.

Mesenchymal Stem Cells Adaptively Respond to Environmental Cues Thereby Improving Granulation Tissue Formation and Wound Healing

Granulation tissue formation constitutes a key step during wound healing of the skin and other organs. Granulation tissue concomitantly initiates regenerative M2 macrophages polarization, fibroblast proliferation, myofibroblast differentiation with subsequent contraction of the wound, new vessel formation, and matrix deposition. Impaired granulation tissue formation either leads to delayed wound healing or excessive scar formation, conditions with high morbidity and mortality. Accumulating evidence has demonstrated that mesenchymal stem cell (MSC)-based therapy is a promising strategy to ameliorate defects in granulation tissue formation and to successfully treat non-healing chronic wounds. In this review we give an updated overview of how therapeutically administered MSCs ensure a balanced granulation tissue formation, and furthermore discuss the cellular and molecular mechanisms underlying the adaptive responses of MSCs to cue in their direct neighborhood. Improved understanding of the interplay between the exogenous MSCs and their niche in granulation tissue will foster the development of MSC-based therapies tailored for difficult-to-treat non-healing wounds.

Extracellular vesicles from adipose-derived stem cells ameliorate ultraviolet B-induced skin photoaging by attenuating reactive oxygen species production and inflammation

BACKGROUND

Large numbers of adipose-derived stem cells (ADSCs) are easily obtained and have been demonstrated to protect against ultraviolet B (UVB)-induced skin photoaging. Extracellular vesicles (EVs) exhibit some of the same effects as the cells from which they originate and have many advantages over stem cells. In particular, their application circumvents many safety concerns associated with cell therapy. Thus, as a cell-free agent, adipose-derived stem cell extracellular vesicles (ADSC-EVs) have anti-photoaging potential. However, the protective effects of ADSC-EVs in skin photoaging remain uncertain.

METHODS

To investigate the effect of ADSC-EVs on mice with UVB-induced photoaging, 150 μg and 300 μg ADSC-EVs were subcutaneously injected weekly into photoaging mice for 8  weeks. The protective effect was evaluated by gross assessment and hematoxylin and eosin, Masson's trichrome, and β-galactosidase staining. Proliferating cell nuclear antigen, CD68, and dihydroethidium staining were performed to evaluate cell proliferation, inflammation infiltration, and reactive oxygen species (ROS) production, respectively. In vitro, 100 μg/mL and 200 μg/mL ADSC-EVs were used to treat photoaging fibroblasts (FBs). β-galactosidase staining and collagen 1 and matrix metalloproteinase 3 (MMP-3) expression were analyzed to evaluate FB senescence. To explain the protective mechanism of ADSC-EVs, their role in regulating ROS production, antioxidant enzyme expression, cell cycle arrest, and inflammation was evaluated.

RESULTS

In vivo, we showed that ADSC-EVs decreased skin wrinkles in mice with UVB-induced photoaging, while promoting epidermal cell proliferation and attenuating macrophage infiltration and ROS production. In vitro, we showed that ADSC-EVs increased FB activity and protected FBs from UVB-induced senescence, attenuated raw 264.7 cell differentiation from M0 to M1 macrophages, reduced intracellular ROS production, promoted antioxidant enzyme expression, and rescued FBs from cell cycle arrest.

CONCLUSION

The anti-photoaging effect of ADSC-EVs was attributed to their ability to attenuate ROS production and the inflammatory response, which are key factors in MMP activation and collagen degradation.

Minicircle-based GCP-2 ex vivo gene therapy enhanced the reepithelialization and angiogenic capacity

Recently, minicircle (MC)-based cell therapy has been emerging as a novel technology for nonviral genetic modification. In this study, we investigated the characteristics of granulocyte chemotactic protein-2 (GCP-2)-overexpressing fibroblasts (GCP-2/MC) using MC microporation technology, as well as its therapeutic mechanism in wound healing. GCP-2 parent plasmid and MC containing GCP-2 were generated. Human dermal fibroblasts (HDF) were transfected with MC containing GCP-2. Quantitative reverse transcription polymerase chain reaction (qRT-PCR), scratch wound assay, and in vivo wound healing assay were performed. Gene and protein expression analysis revealed that GCP-2/MC highly expressed epithelialization growth factor, epidermal growth factor (EGF), chemokines, GCP-2, interleukin (IL)-8, as well as wound healing-associated genes such as insulin growth factor (IGF)-1 and hepatocyte growth factor (HGF). An in vitro scratch wound closure and matrigel tube formation assays demonstrated that the culture medium derived from GCP-2/MC substantially accelerated the wound closure and matrigel network formation. Wounds in nude mice were created by skin excisions followed by injections of GCP-2/MC. Results showed high cell survival potential and that GCP-2/MC transplantation highly accelerated skin wound closure by increasing reepithelialization, capillary density, and enhancing angiogenic factors, suggesting direct benefits for cutaneous closure. Taken together, these data suggest that MC-based GCP-2 overexpression could be a promising alternative strategy for promoting wound healing.

Lung-resident mesenchymal stromal cells are tissue-specific regulators of lung homeostasis

Until recently, data supporting the tissue-resident status of mesenchymal stromal cells (MSC) has been ambiguous since their discovery in the 1950-60s. These progenitor cells were first discovered as bone marrow-derived adult multipotent cells and believed to migrate to sites of injury, opposing the notion that they are residents of all tissue types. In recent years, however, it has been demonstrated that MSC can be found in all tissues and MSC from different tissues represent distinct populations with differential protein expression unique to each tissue type. Importantly, these cells are efficient mediators of tissue repair, regeneration, and prove to be targets for therapeutics, demonstrated by clinical trials (phase 1-4) for MSC-derived therapies for diseases like graft-versus-host-disease, multiple sclerosis, rheumatoid arthritis, and Crohn's disease. The tissue-resident status of MSC found in the lung is a key feature of their importance in the context of disease and injuries of the respiratory system, since these cells could be instrumental to providing more specific and targeted therapies. Currently, bone marrow-derived MSC have been established in the treatment of disease, including diseases of the lung. However, with lung-resident MSC representing a unique population with a different phenotypic and gene expression pattern than MSC derived from other tissues, their role in remediating lung inflammation and injury could provide enhanced efficacy over bone marrow-derived MSC methods. Through this review, lung-resident MSC will be characterized, using previously published data, by surface markers, gene expression patterns, and compared with bone-marrow MSC to highlight similarities and, importantly, differences in these cell types.

Single-cell transcriptomes of the human skin reveal age-related loss of fibroblast priming

Fibroblasts are an essential cell population for human skin architecture and function. While fibroblast heterogeneity is well established, this phenomenon has not been analyzed systematically yet. We have used single-cell RNA sequencing to analyze the transcriptomes of more than 5,000 fibroblasts from a sun-protected area in healthy human donors. Our results define four main subpopulations that can be spatially localized and show differential secretory, mesenchymal and pro-inflammatory functional annotations. Importantly, we found that this fibroblast 'priming' becomes reduced with age. We also show that aging causes a substantial reduction in the predicted interactions between dermal fibroblasts and other skin cells, including undifferentiated keratinocytes at the dermal-epidermal junction. Our work thus provides evidence for a functional specialization of human dermal fibroblasts and identifies the partial loss of cellular identity as an important age-related change in the human dermis. These findings have important implications for understanding human skin aging and its associated phenotypes.

Single-cell transcriptional diversity is a hallmark of developmental potential

Single-cell RNA sequencing (scRNA-seq) is a powerful approach for reconstructing cellular differentiation trajectories. However, inferring both the state and direction of differentiation is challenging. Here, we demonstrate a simple, yet robust, determinant of developmental potential-the number of expressed genes per cell-and leverage this measure of transcriptional diversity to develop a computational framework (CytoTRACE) for predicting differentiation states from scRNA-seq data. When applied to diverse tissue types and organisms, CytoTRACE outperformed previous methods and nearly 19,000 annotated gene sets for resolving 52 experimentally determined developmental trajectories. Additionally, it facilitated the identification of quiescent stem cells and revealed genes that contribute to breast tumorigenesis. This study thus establishes a key RNA-based feature of developmental potential and a platform for delineation of cellular hierarchies.

Human umbilical cord mesenchymal stem cell-derived and dermal fibroblast-derived extracellular vesicles protect dermal fibroblasts from ultraviolet radiation-induced photoaging in vitro

Ultraviolet B (UVB) radiation is a major cause of aging in dermal fibroblasts. Human umbilical cord mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) show antioxidant activity. In this study, the anti-aging effects of MSC-EVs on dermal fibroblast photoaging induced by UVB radiation were evaluated, and the effects of extracellular vesicles derived from dermal fibroblasts (Fb-EVs) were compared. Human umbilical cord mesenchymal stem cells and human dermal fibroblasts were cultured, and MSC-EVs and Fb-EVs were isolated and characterized. Human dermal fibroblasts were cultured in the absence or presence of different concentrations of EVs 24 hours prior to UVB radiation exposure. Cell proliferation and cell cycle were evaluated, and senescent cells and intracellular ROS were detected. The expressions of matrix metalloproteinase-1 (MMP-1), extracellular matrix protein collagen type 1 (Col-1), and antioxidant proteins such as glutathione peroxidase 1 (GPX-1), superoxide dismutase (SOD), and catalase were also analyzed. Pretreatment with MSC-EVs or Fb-EVs significantly inhibited the production of ROS induced by UVB radiation, increased dermal fibroblast proliferation, protected cells against UVB-induced cell death and cell cycle arrest, and remarkably decreased the percentage of aged cells. Pretreatment with MSC-EVs or Fb-EVs promoted the expressions of GPX-1 and Col-1 and decreased the expression of MMP-1. Both MSC-EVs and Fb-EVs protected dermal fibroblasts from UVB-induced photoaging, likely through their antioxidant activity.

Adipose-derived stromal/stem cells improve epidermal homeostasis

Wound healing is regulated by complex interactions between the keratinocytes and other cell types including fibroblasts. Recently, adipose-derived mesenchymal stromal/stem cells (ASCs) have been reported to influence wound healing positively via paracrine involvement. However, their roles in keratinocytes are still obscure. Therefore, investigation of the precise effects of ASCs on keratinocytes in an in vitro culture system is required. Our recent data indicate that the epidermal equivalents became thicker on a collagen vitrigel membrane co-cultured with human ASCs (hASCs). Co-culturing the human primary epidermal keratinocytes (HPEK) with hASCs on a collagen vitrigel membrane enhanced their abilities for cell proliferation and adhesion to the membrane but suppressed their differentiation suggesting that hASCs could maintain the undifferentiated status of HPEK. Contrarily, the effects of co-culture using polyethylene terephthalate or polycarbonate membranes for HPEK were completely opposite. These differences may depend on the protein permeability and/or structure of the membrane. Taken together, our data demonstrate that hASCs could be used as a substitute for fibroblasts in skin wound repair, aesthetic medicine, or tissue engineering. It is also important to note that a co-culture system using the collagen vitrigel membrane allows better understanding of the interactions between the keratinocytes and ASCs.

Asiatic Acid Glucosamine Salt Alleviates Ultraviolet B-induced Photoaging of Human Dermal Fibroblasts and Nude Mouse Skin

Herbal extracts including asiatic acid (AA) have become popular candidates of anti-photoaging agents due to their anti-inflammatory and antioxidant properties and minimal side effect. Nevertheless, low bioavailability due to poor solubility limits their practical application. In this study, a highly bioavailable form of AA called AAGS (compounded by asiatic acid and glucosamine) was investigated for its anti-photoaging effect using both in vitro and in vivo models along with UVB irradiation. The results showed that AAGS alleviated UVB-induced cell proliferation inhibition by reducing G2 phase arrest and cell apoptosis rate as well as the gene expressions of P53, BAX, CASPASE 3 and CASPASE 9, but enhancing BCL-2 expression. It also reduced the production of reactive oxygen species along with increased gene expression of GPX-1 and downregulated the gene expression of IL-1β, IL-6, IL-8, IL-17 and TNF-α compared to nontreated cells. In vivo results demonstrated the antiphotodamaging effects by restoring skin thickness, collagen content and reducing MMPs expression, which are also supported by reduced MMPs gene expression and enhanced collagen I and TGF-β1 gene expression in vitro. Thus, AAGS may become a potential anti-photoaging agent for topical use due to its capability of self-assembling into a water gel.

Isolation, Characterization, and Safety Evaluation of Human Skin-Derived Precursors from an Adherent Monolayer Culture System

BACKGROUND

Skin-derived precursors (SKPs) are promising candidates for regenerative medicine. Several studies have transcultured human SKPs (termed tSKPs) from fibroblasts (FBs) expanded in monolayer culture. Herein, we optimized the procedure by treating flasks with poly-2-hydroxyethyl methacrylate (poly-HEMA).

METHODS

tSKPs generated from our adherent monolayer culture system were investigated for protein expression and differentiation capacity. The aggregated cells and the proliferative cells within tSKP spheres were detected by mix-culturing FBs expressing two different fluorescent proteins and BrdU- or EdU-positive cells, respectively. To distinguish tSKPs from FBs, we compared their phenotypes and transcriptomes. The tumorigenicity of tSKPs and FBs was also assessed in our study.

RESULTS

tSKPs expressed Versican, Fibronectin, Vimentin, Sox2, and Nestin. Under appropriate stimuli, tSKPs could differentiate to mesenchymal or neural lineages. While these spheres were heterogeneous populations consisting of both proliferative and aggregated cells, the rate of proliferative cells correlated with a seeding density. tSKPs, isolated from FBs, were distinctive from FBs in cell cycle, marker expression, neural differentiation potential, and transcript profiles despite the two sharing partial similarity in certain properties. As for tumorigenesis, both tSKPs and FBs could be considered as nontumorigenic ex vivo and in vivo.

CONCLUSION

tSKPs were heterogeneous populations presenting similar characteristics as traditional SKPs, while being different from FBs. The potential mixture of FBs in spheres did not affect the biosafety of tSKPs, as both of which had normal karyotype and nontumorigenicity. Taken together, we suggested tSKPs had potential applications in regenerative medicine.

Protective Effect of Fat Extract on UVB-Induced Photoaging In Vitro and In Vivo

Background

Nanofat can protect against ultraviolet B- (UVB-) induced damage in nude mice. Fat extract (FE) is a cell-free fraction isolated from nanofat that is enriched with a variety of growth factors.

Objective

To determine whether FE can protect against UVB-induced photoaging in cultured dermal fibroblasts and in nude mice.

Method

For the in vitro study, human dermal skin fibroblasts were pretreated with FE 24 h prior to UVB irradiation. Generation of reactive oxygen species (ROS) was analyzed immediately following irradiation, while cell cycle analysis was performed 24 h after UVB irradiation. Senescence-associated β-galactosidase (SA-β-gal) expression, cell proliferation, and expression of glutathione peroxidase 1 (GPX-1), catalase, superoxide dismutase-1 (SOD-1), SOD-2, and collagen type 1 (COL-1) were investigated 72 h after UVB irradiation. For the in vivo study, the dorsal skin of nude mice was irradiated with UVB and mice were then treated with FE for 8 weeks. The thickness of the dermis, capillary density, and apoptotic cells in skin tissue sections were investigated after treatment. The expression of GPX-1, catalase, SOD-2, SOD-1, and COL-1 in the tissue was also measured.

Result

FE significantly increased cell proliferation and protected cells against UVB-induced cell death and cell cycle arrest. FE reduced ROS and the number of aged cells induced by UVB irradiation. FE promoted the expression of COL-1 and GPX-1 in cultured dermal fibroblasts. FE treatment of UVB-irradiated skin increased dermal thickness and capillary density, decreased the number of apoptotic cells, and promoted the expression of COL-1 and GPX-1.

Conclusion

FE protects human dermal fibroblasts and the skin of nude mice from UVB-induced photoaging through its antioxidant, antiapoptotic, and proangiogenic activities.

Development of de novo epithelialization method for treatment of cutaneous ulcers

Cutaneous ulcers are a common cause of morbidity. We have developed a de novo epithelialization method for treating cutaneous ulcers by means of reprogramming wound-resident mesenchymal cells in vivo into cells able to form a stratified epithelium: induced stratified epithelial progenitors (iSEPs). Administration of 4 transcription factors (DNP63A, GRHL2, TFAP2A, and cMYC) expressed via adeno-associated viral vectors enabled generation of epithelial cells and tissues, thereby acheiving de novo epithelialization from the surfaces of cutaneous ulcers in a mouse model. Generated epithelia, having barrier functions equivalent to the original epidermis, were maintained for more than 6 months. Our findings constitute a proof of concept for future development towards innovative therapies for cutaneous ulcers via de novo epithelialization.

Isolation and Culture of Skin-Derived Differentiated and Stem-Like Cells Obtained from the Arabian Camel (Camelus dromedarius)

Simple Summary

This is the first comprehensive study to isolate different cellular types and stem-like cells from the camel skin. We reported the multipotency of the isolated stem cells. Moreover, some unique cells were observed, such as dermal cyst-forming cells. This discovery represents a cheap and easy source for camel stem cells that is essential for development of the elite camel regenerative medicine and provides a good source of camel fibroblast required for camel cloning.

Abstract

Elite camels often suffer from massive injuries. Thus, there is a pivotal need for a cheap and readily available regenerative medicine source. We isolated novel stem-like cells from camel skin and investigated their multipotency and resistance against various stresses. Skin samples were isolated from ears of five camels. Fibroblasts, keratinocytes, and spheroid progenitors were extracted. After separation of different cell lines by trypsinization, all cell lines were exposed to heat shock. Then, fibroblasts and dermal cyst-forming cells were examined under cryopreservation. Dermal cyst-forming cells were evaluated for resistance against osmotic pressure. The results revealed that resistance periods against trypsin were 1.5, 4, and 7 min for fibroblasts, keratinocytes, and spheroid progenitors, respectively. Furthermore, complete recovery of different cell lines after heat shock along with the differentiation of spheroid progenitors into neurons was observed. Fibroblasts and spheroid progenitors retained cell proliferation after cryopreservation. Dermal cyst-forming cells regained their normal structure after collapsing by osmotic pressure. The spheroid progenitors incubated in the adipogenic, osteogenic, and neurogenic media differentiated into adipocyte-, osteoblast-, and neuron-like cells, respectively. To the best of our knowledge, we isolated different unique cellular types and stem-like cells from the camel skin and examined their multipotency for the first time.

When the skin is in the center of interest: An aging issue

The skin represents the first bearer of marks of time as well as an easily accessible model for the assessment and determination of the involved molecular mechanisms. The deterioration of important skin functions due to intrinsic and extrinsic aging leads to clinical manifestations, which mirror several internal age-associated diseases, such as neurodegenerative, cardiovascular, skeletal, and endocrine/metabolic skin diseases. Current molecular data indicate that skin aging, especially intrinsic aging, mirrors age-related deficiencies in the entire human body. These data and the development of new biologic technologies highlight the importance of the skin in aging research and should enable future interdisciplinary projects on internal diseases, which could barely have been performed until recently due mainly to the lack of respective tissue.

Bone morphogenetic protein 7 enhances the osteogenic differentiation of human dermal-derived CD105+ fibroblast cells through the Smad and MAPK pathways

The skin, as the largest organ of the human body, is an important source of stromal stem cells with multipotent differentiation potential. CD105⁺ mesenchymal stem cells exhibit a higher level of stemness than CD105⁻ cells. In the present study, human dermal-derived CD105⁺ fibroblast cells (CD105⁺ hDDFCs) were isolated from human foreskin specimens using immunomagnetic isolation methods to examine the role of bone morphogenetic protein (BMP)-7 in osteogenic differentiation. Adenovirus-mediated recombinant BMP7 expression enhanced osteogenesis-associated gene expression, calcium deposition, and alkaline phosphatase activity. Investigation of the underlying mechanisms showed that BMP7 activated small mothers against decapentaplegic (Smad) and p38/mitogen-activated protein kinase signaling in CD105⁺ hDDFCs. The small interfering RNA-mediated knockdown of Smad4 or inhibition of p38 attenuated the BMP7-induced enhancement of osteogenic differentiation. In an in vivo ectopic bone formation model, the adenovirus-mediated overexpression of BMP7 enhanced bone formation from CD105⁺ hDDFCs. Taken together, these data indicated that adenoviral BMP7 gene transfer in CD105⁺ hDDFCs may be developed as an effective tool for bone tissue engineering.

Isolation and biological characterization of mesenchymal stem cells from goose dermis

The skin is a natural target of stem cell research because of its large size and easy accessibility. Cutaneous mesenchymal stem cells have shown to be a promising source of various adult stem cell or progenitor cell populations, which provide an important source of stem cell-based investigation. Nowadays, much work has been done on dermal-derived mesenchymal stem cells (DMSCs) from humans, mice, sheep, and other mammals, but the literature on avian species has been rarely reported. As an animal model, the goose is an endemic species abounding in dermal tissues which is important in the global economy. In this study, we isolated and established the mesenchymal stem cell line from dermis tissue of goose, which were subcultured to passage 21 in vitro without loss of their functional integrity in terms of morphology, renewal capacity, and presence of mesenchymal stem cell markers. Cryopreservation and resuscitation were also observed in different passages. To investigate the biological characteristics of goose DMSCs, immunofluorescence, reverse transcription-polymerase chain reaction, and flow cytometry were used to detect the characteristic surface markers. Growth curves and the capacity of colony forming were performed to test the self-renew and proliferative ability. Furthermore, the DMSCs are induced to osteoblasts, adipocytes, and chondrocytes in vitro. Our results suggest that DMSCs isolated from goose embryos possess similar biological characteristics to those from other species. The methods in establishment and cultivation of goose DMSCs line demonstrated a good self-renew and expansion potential in vitro, which provided a technological platform for preserving the valuable genetic resources of poultry and a great inspiration for in vitro investigation of avian MSCs.

Lineage Identity and Location within the Dermis Determine the Function of Papillary and Reticular Fibroblasts in Human Skin

Human skin dermis is composed of the superficial papillary dermis and the reticular dermis in the lower layers, which can easily be distinguished histologically. In vitro analyses of fibroblasts from explant cultures from superficial and lower dermal layers suggest that human skin comprises at least two fibroblast lineages with distinct morphology, expression profiles, and functions. However, while for mouse skin cell surface markers have been identified, allowing the isolation of pure populations of one lineage or the other via FACS, this has not been achieved for human skin fibroblasts. We have now discovered two cell surface markers that discriminate between papillary and reticular fibroblasts. While FAP⁺CD90^- cells display increased proliferative potential, express PDPN and NTN1, and cannot be differentiated into adipocytes, FAP^-CD90⁺ fibroblasts express high levels of ACTA2, MGP, PPARγ, and CD36 and readily undergo adipogenic differentiation, a hallmark of reticular fibroblasts. Flow cytometric analysis of fibroblasts isolated from superficial and lower layers of human dermis showed that FAP⁺CD90^- cells are enriched in the papillary dermis. Altogether, functional analysis and expression profiling confirms that FAP⁺CD90^- cells represent papillary fibroblasts, whereas FAP^-CD90⁺ fibroblasts derive from the reticular lineage. Although papillary and reticular fibroblasts are enriched in the upper or lower dermis, respectively, they are not spatially restricted, and the microenvironment seems to affect their function.

Eminent Sources of Adult Mesenchymal Stem Cells and Their Therapeutic Imminence

In the recent times, stem cell biology has garnered the attention of the scientific fraternity and the general public alike due to the immense therapeutic potential that it holds in the field of regenerative medicine. A breakthrough in this direction came with the isolation of stem cells from human embryo and their differentiation into cell types of all three germ layers. However, the isolation of mesenchymal stem cells from adult tissues proved to be advantageous over embryonic stem cells due to the ethical and immunological naivety. Mesenchymal Stem Cells (MSCs) isolated from the bone marrow were found to differentiate into multiple cell lineages with the help of appropriate differentiation factors. Furthermore, other sources of stem cells including adipose tissue, dental pulp, and breast milk have been identified. Newer sources of stem cells have been emerging recently and their clinical applications are also being studied. In this review, we examine the eminent sources of Mesenchymal Stem Cells (MSCs), their immunophenotypes, and therapeutic imminence.

Protective effect of crocin on ultraviolet B‑induced dermal fibroblast photoaging

Ultraviolet B (UVB) radiation induces the production of reactive oxygen species (ROS), resulting in the aging of dermal fibroblasts. Crocin, a bioactive constituent of Crocus sativus, possesses anti‑oxidation effects. The purpose of the present study was to evaluate the protective effect of crocin on UVB‑induced dermal fibroblast photoaging. Human dermal fibroblasts were isolated and cultured with different concentrations of crocin prior to and following exposure to UVB irradiation. The senescent phenotypes of cells were evaluated, including cell proliferation, cell cycle, senescence‑associated β‑galactosidase (SA‑β‑gal) expression, intracellular ROS, expression of antioxidant protein glutathione peroxidase 1 (GPX‑1) and extracellular matrix protein collagen type 1 (Col‑1). Crocin rescued the cell proliferation inhibited by UVB irradiation, prevented cell cycle arrest and markedly decreased the number of SA‑β‑gal‑positive cells. In addition, crocin reduced UVB‑induced ROS by increasing GPX‑1 expression and other direct neutralization effects. Furthermore, crocin promoted the expression of the extracellular matrix protein Col‑1. Crocin could effectively prevent UVB‑induced cell damage via the reduction of intracellular ROS; thus, it could potentially be used in the prevention of skin photoaging.

Bone morphogenetic protein 7-transduced human dermal-derived fibroblast cells differentiate into osteoblasts and form bone in vivo

BACKGROUND

Human dermal-derived fibroblast cells (hDDFCs) are multipotent. Bone morphogenetic proteins (BMPs) are a group of cytokines that promote different developmental processes, including the formation of bone. BMPs can promote hDDFC osteogenesis, but the role of BMP7 in hDDFC osteogenesis in vitro and bone formation in vivo has not been investigated in depth.

MATERIALS AND METHODS

hDDFCs were stably transfected with a human BMP7 recombinant adenovirus and osteogenic differentiation was examined by alkaline phosphatase staining and calcium accumulation. In addition, we measured the expression of osteoblast-related genes. To examine osteogenesis in vivo, we injected C57BL/6 nude mice with adenovirus-transfected hDDFCs in a calcium alginate hydrogel and examined bone formation using soft X-ray, histological, and immunohistochemical analyses.

RESULTS

Our findings showed that adenovirus-mediated BMP7 expression promoted osteogenic differentiation of hDDFCs and enhanced expression of osteoblast-related genes in vitro. Cells infected with BMP7 adenoviruses showed enhanced bone formation and osteoblast-related gene expression in vivo after the injection of hDDFC-hydrogel mixture.

CONCLUSIONS

Taken together, our data indicate that BMP7 significantly promotes hDDFC osteogenesis, and confirm that infecting hDDFCs with BMP7-expressing adenoviruses is a useful tool for bone tissue engineering.

Human dental stem cell derived transgene-free iPSCs generate functional neurons via embryoid body-mediated and direct induction methods

Induced pluripotent stem cells (iPSCs) give rise to neural stem/progenitor cells, serving as a good source for neural regeneration. Here, we established transgene-free (TF) iPSCs from dental stem cells (DSCs) and determined their capacity to differentiate into functional neurons in vitro. Generated TF iPSCs from stem cells of apical papilla and dental pulp stem cells underwent two methods-embryoid body-mediated and direct induction, to guide TF-DSC iPSCs along with H9 or H9 Syn-GFP (human embryonic stem cells) into functional neurons in vitro. Using the embryoid body-mediated method, early stage neural markers PAX6, SOX1, and nestin were detected by immunocytofluorescence or reverse transcription-real time polymerase chain reaction (RT-qPCR). At late stage of neural induction measured at Weeks 7 and 9, the expression levels of neuron-specific markers Nav1.6, Kv1.4, Kv4.2, synapsin, SNAP25, PSD95, GAD67, GAP43, and NSE varied between stem cells of apical papilla iPSCs and H9. For direct induction method, iPSCs were directly induced into neural stem/progenitor cells and guided to become neuron-like cells. The direct method, while simpler, showed cell detachment and death during the differentiation process. At early stage, PAX6, SOX1 and nestin were detected. At late stage of differentiation, all five genes tested, nestin, βIII-tubulin, neurofilament medium chain, GFAP, and Nav, were positive in many cells in cultures. Both differentiation methods led to neuron-like cells in cultures exhibiting sodium and potassium currents, action potential, or spontaneous excitatory postsynaptic potential. Thus, TF-DSC iPSCs are capable of undergoing guided neurogenic differentiation into functional neurons in vitro, thereby may serve as a cell source for neural regeneration.

One-Step Simple Isolation Method to Obtain Both Epidermal and Dermal Stem Cells from Human Skin Specimen

Stem cells play a crucial role in maintaining and repairing tissues during homeostasis and following injury. The efficient procurement of high quantity and quality of skin stem cells is important for both laboratory studies and clinical applications. Here, we describe a one-step isolation procedure to efficiently obtain both epidermal and dermal cell population from human skin specimen, based on the different influence of the Rho kinase inhibitor Y27632 on the growth of epidermal and dermal cells during the initial culture. Compared with the conventional methods, our protocol shows that it is simpler and less time consuming and can efficiently obtain the high quality of skin stem cells and can maintain the stem cell features after culture expansion.