Evaluation of secretomes derived from human dermal and adipose tissue mesenchymal stem/stromal cells for skin wound healing: not as effective as cells.

BACKGROUND: Although the paracrine effects of mesenchymal stem/stromal cells (MSCs) have been recognized as crucial mediators of their regenerative effects on tissue repair, the potential of MSC secretomes as effective substitutes for cellular therapies remains underexplored. METHODS: In this study, we compared MSCs from the human dermis (DSCs) and adipose tissue (ASCs) with their secretomes regarding their efficacy for skin wound healing using a translationally relevant murine model. RESULTS: Proteomic analysis revealed that while there was a substantial overlap in protein composition between DSC and ASC secretomes, specific proteins associated with wound healing and angiogenesis were differentially expressed. Despite a similar angiogenic potential in vivo, DSC and ASC secretomes were found to be less effective than cells in accelerating wound closure and promoting tissue remodeling. CONCLUSIONS: Overall, secretome-treated groups showed intermediary results between cells- and control-treated (empty scaffold) groups. These findings highlight that although secretomes possess therapeutic potential, their efficacy might be limited compared to cellular therapies. This study contributes to the growing understanding of MSC secretomes, emphasizes the need for further protocol optimization, and offers insights into their potential applications in regenerative medicine.

Mesenchymal Stromal Cell Secretome for Therapeutic Application in Skin Wound Healing: A Systematic Review of Preclinical Studies.

Non-healing skin wounds remain a challenge in the healthcare system. In this sense, it is suggested that the secretome of mesenchymal stromal cells (MSCs) can be effective as a therapeutic strategy for regenerative medicine. Therefore, this systematic review aimed to determine the effects of treatment with a secretome derived from MSCs on the healing of skin wounds in a preclinical model of rodents (mice and rats). Studies were systematically retrieved from 6 databases and gray literature that provided 1,172 records, of which 25 met the inclusion criteria for qualitative analysis. Results revealed substantial heterogeneity among studies concerning experimental designs and methodologies, resulting in a high risk of bias. Together, the selected studies reported that treatment improved wound healing by (1) accelerating wound closure and improving skin repair quality; (2) reducing inflammation by decreasing the number of cells and inflammatory cytokines, accompanied by polarization of the M2 macrophage; (3) complete re-epithelialization and epidermal reorganization; (4) neovascularization promoted by proliferation of endothelial cells (CD34+) and increased levels of pro-angiogenic mediators; (5) better scar quality promoted by increased expression of collagen types I and III, as well as improved deposition and remodeling of collagen fibers. In conclusion, despite the need for alignment of methodological protocols and transparent reports in future studies, results show that the secretome of MSCs from different tissue sources corresponds to a promising tool of regenerative medicine for the treatment of skin wounds.

Fibroblast growth factor-2 bound to specific dermal fibroblast-derived extracellular vesicles is protected from degradation.

Fibroblast growth factor-2 (FGF2) has multiple roles in cutaneous wound healing but its natural low stability prevents the development of its use in skin repair therapies. Here we show that FGF2 binds the outer surface of dermal fibroblast (DF)-derived extracellular vesicles (EVs) and this association protects FGF2 from fast degradation. EVs isolated from DF cultured in the presence of FGF2 harbor FGF2 on their surface and FGF2 can bind purified EVs in absence of cells. Remarkably, FGF2 binding to EVs is restricted to a specific subpopulation of EVs, which do not express CD63 and CD81 markers. Treatment of DF with FGF2-EVs activated ERK and STAT signaling pathways and increased cell proliferation and migration. Local injection of FGF2-EVs improved wound healing in mice. We further demonstrated that binding to EVs protects FGF2 from both thermal and proteolytic degradation, thus maintaining FGF2 function. This suggests that EVs protect soluble factors from degradation and increase their stability and half-life. These results reveal a novel aspect of EV function and suggest EVs as a potential tool for delivering FGF2 in skin healing therapies.

Human adipose-derived mesenchymal stromal cells from face and abdomen undergo replicative senescence and loss of genetic integrity after long-term culture.

Body fat depots are heterogeneous concerning their embryonic origin, structure, exposure to environmental stressors, and availability. Thus, investigating adipose-derived mesenchymal stromal cells (ASCs) from different sources is essential to standardization for future therapies. In vitro amplification is also critical because it may predispose cell senescence and mutations, reducing regenerative properties and safety. Here, we evaluated long-term culture of human facial ASCs (fASCs) and abdominal ASCs (aASCs) and showed that both met the criteria for MSCs characterization but presented differences in their immunophenotypic profile, and differentiation and clonogenic potentials. The abdominal tissue yielded more ASCs, and these had higher proliferative potential, but facial cells displayed fewer mitotic errors at higher passages. However, both cell types reduced clonal efficiency over time and entered replicative senescence around P12, as evaluated by progressive morphological alterations, reduced proliferative capacity, and SA-ß-galactosidase expression. Loss of genetic integrity was detected by a higher proportion of cells showing nuclear alterations and γ-H2AX expression. Our findings indicate that the source of ASCs can substantially influence their phenotype and therefore should be carefully considered in future cell therapies, avoiding, however, long-term culture to ensure genetic stability.

Administration of mesenchymal stem cells from adipose tissue at the hip joint of dogs with osteoarthritis: A systematic review.

This systematic review aimed to determine the effects of intra-articular administration of mesenchymal stem cells from adipose tissue in dogs with hip joint osteoarthritis (OA). Clinical trials were systematically reviewed, using PubMed, EMBASE, Cochrane Library, LILACS, Web of Science, Scopus, Open Grey, Google Scholar, and ProQuest Dissertation and Thesis without publication year restrictions. References were screened and selected based on predefined eligibility criteria by two independent reviewers, according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Clinical outcomes were assessed quantitatively using clinical pain scores, physical examination, imaging examination, questionnaire responses, pain in manipulation, gait analysis, range of joint motion, and adverse effects. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist. Out of 1483 articles, six met the inclusion criteria for qualitative analysis, with two randomized controlled trials and four before-and-after studies. All studies reported significantly better clinical outcomes in the adipose tissue stem cells (ADSC) group with improvements in pain and function and decreased evidence of hip OA. The risk of bias was categorized as high in the before-and-after studies and moderate to high in the randomized studies. The studies were considered heterogeneous owing to clinical results and methodology. Because of this heterogeneity, it was not possible to perform meta-analysis. Assessments of ADSC reports yielded positive clinical effects that showed improvements in pain and function and decreased evidence of hip osteoarthritis. More high-level, larger-cohort dog studies that utilize standardized protocols are needed.

Mesenchymal stromal cells from dermal and adipose tissues induce macrophage polarization to a pro-repair phenotype and improve skin wound healing.

The process of wound healing restores skin homeostasis but not full functionality; thus, novel therapeutic strategies are needed to accelerate wound closure and improve the quality of healing. In this context, tissue engineering and cellular therapies are promising approaches. Although sharing essential characteristics, mesenchymal stromal cells (MSCs) isolated from different tissues might have distinct properties. Therefore, the aim of this study was to comparatively investigate, by a mouse model in vivo assay, the potential use of dermal-derived MSCs (DSCs) and adipose tissue-derived MSCs (ASCs) in improving skin wound healing. Human DSCs and ASCs were delivered to full-thickness mouse wounds by a collagen-based scaffold (Integra Matrix). We found that the association of both DSCs and ASCs with the Integra accelerated wound closure in mice compared with the biomaterial only (control). Both types of MSCs stimulated angiogenesis and extracellular matrix remodeling, leading to better quality scars. However, the DSCs showed smaller scar size,superior extracellular matrix deposition, and greater number of cutaneous appendages. Besides, DSCs and ASCs reduced inflammation by induction of macrophage polarization from a pro-inflammatory (M1) to a pro-repair (M2) phenotype. In conclusion, both DSCs and ASCs were able to accelerate the healing of mice skin wounds and promote repair with scars of better quality and more similar to healthy skin than the empty scaffold. DSCs associated with Integra induced superior overall results than the Integra alone, whereas scaffolds with ASCs showed an intermediate effect, often not significantly better than the empty biomaterial.

FGF2 Stimulates the Growth and Improves the Melanocytic Commitment of Trunk Neural Crest Cells.

Neural crest cells (NCCs) comprise a population of multipotent progenitors and stem cells at the origin of the peripheral nervous system (PNS) and melanocytes of skin, which are profoundly influenced by microenvironmental factors, among which is basic fibroblast growth factor 2 (FGF2). In this work, we further investigated the role of this growth factor in quail trunk NC morphogenesis and demonstrated its huge effect in NCC growth mainly by stimulating cell proliferation but also reducing cell death, despite that NCC migration from the neural tube explant was not affected. Moreover, following FGF2 treatment, reduced expression of the early NC markers Sox10 and FoxD3 and improved proliferation of HNK1-positive NCC were observed. Since these markers are involved in the regulation of glial and melanocytic fate of NC, the effect of FGF2 on NCC differentiation was investigated. Therefore, in the presence of FGF2, increased proportions of NCCs positives to the melanoblast marker Mitf as well as NCCs double stained to Mitf and BrdU were recorded. In addition, treatment with FGF2, followed by differentiation medium, resulted in increased expression of melanin and improved proportion of melanin-pigmented melanocytes without alteration in the glial marker Schwann myelin protein (SMP). Taken together, these data further reveal the important role of FGF2 in NCC proliferation, survival, and differentiation, particularly in melanocyte development. This is the first demonstration of FGF2 effects in melanocyte commitment of NC and in the proliferation of Mitf-positive melanoblasts. Elucidating the differentiation process of embryonic NCCs brings us a step closer to understanding the development of the PNS and then undertaking the search for advanced technologies to prevent, or treat, injuries caused by NC-related disorders, also known as neurocristopathies.

Human Dental Pulp Stem Cells in Rat Mandibular Bone Defects.

This study aimed to evaluate the use of human dental pulp stem cells (hDPSCs) in non-critical-sized mandibular bone defects in rats. hDPSCs from permanent teeth were isolated and engrafted in mandibular bone defects in rats for 7, 14, and 28 days; bone defects without cells formed the control group. Samples were evaluated by scanning electron microscopy (SEM), light microscopy (hematoxylin and eosin staining), and the regeneration area was measured by the Image J program. Before surgery procedures, the human dental pulp cells were characterized as dental pulp stem cells: fusiform morphology, plastic-adherent; expression of CD105, CD73, and CD90; lack of expression of CD45 and CD34, and differentiated into osteoblasts, adipocytes, and chondroblasts. The results indicated that within 7 days the control group presented a pronounced bone formation when compared with the treated group (p < 0.05). After 14 days, the treated group showed an increase in bone formation, but with no statistical difference among the groups (p > 0.05). In the final evaluated period there was no difference between the control group and the treated group (p > 0.05). There was a significant difference between 7 and 14 days (p < 0.05) and between 7 and 28 days (p < 0.05) in the treated group. In conclusion, there is no evidence that the use of hDPSCs in the conditions of this study could improve bone formation in non-critical-sized mandibular bone defects.

In vitro comparative study of human mesenchymal stromal cells from dermis and adipose tissue for application in skin wound healing.

Novel strategies combining cell therapy, tissue engineering, and regenerative medicine have been developed to treat major skin wounds. Although mesenchymal stromal cells (MSCs) from different tissues have similar stem cell features, such as self-renewing mesodermal differentiation potential and expression of immunophenotypic markers, they also have distinct characteristics. Therefore, we aimed to characterize the application of MSCs derived from the dermis and adipose tissue (DSCs and ASCs, respectively) in cutaneous wound healing by in vitro approaches. Human DSC and ASC were obtained and evaluated for their isolation efficiency, stemness, proliferative profile, and genetic stability over time in culture. The ability of wound closure was first assessed by direct cell scratch assay. The paracrine effects of DSC- and ASC-conditioned medium in dermal fibroblasts and keratinocytes and in the induction of tubule formation were also investigated. Although the ASC isolation procedures resulted in 100 times more cells than DSC, the latter had a higher proliferation rate in culture. Both presented low frequency of nuclear alterations over time in culture and showed similar characteristics of stem cells, such as expression of immunophenotypic markers and differentiation potential. DSCs showed increased healing capacity, and their conditioned media had greater paracrine effect in closing the wound of dermal fibroblasts and keratinocytes and in inducing angiogenesis. In conclusion, the therapeutic potential of MSCs is influenced by the obtainment source. Both ASCs and DSCs are applicable for skin wound healing; however, DSCs have an improved potential and should be considered for future applications in cell therapy.

Distinct features of rabbit and human adipose-derived mesenchymal stem cells: implications for biotechnology and translational research.

INTRODUCTION: Owing to their similarity with humans, rabbits are useful for multiple applications in biotechnology and translational research from basic to preclinical studies. In this sense, mesenchymal stem cells (MSCs) are known for their therapeutic potential and promising future in regenerative medicine. As many studies have been using rabbit adipose-derived MSCs (ASCs) as a model of human ASCs (hASCs), it is fundamental to compare their characteristics and understand how distinct features could affect the translation to human medicine. OBJECTIVE: The aim of this study was to comparatively characterize rabbit ASCs (rASCs) and hASCs to further uses in biotechnology and translational studies. MATERIALS AND METHODS: rASCs and hASCs were isolated and characterized by their immunophenotype, differentiation potential, proliferative profile, and nuclear stability in vitro. RESULTS AND DISCUSSION: Both ASCs presented differentiation potential to osteocytes, chondrocytes, and adipocytes and shared similar immunophenotype expression to CD105+, CD34-, and CD45-, but rabbit cells expressed significantly lower CD73 and CD90 than human cells. In addition, rASCs presented greater clonogenic potential and proliferation rate than hASCs but no difference in nuclear alterations. CONCLUSION: The distinct features of rASCs and hASCs can positively or negatively affect their use for different applications in biotechnology (such as cell reprogramming) and translational studies (such as cell transplantation, tissue engineering, and pharmacokinetics). Nevertheless, the particularities between rabbit and human MSCs should not prevent rabbit use in preclinical models, but care should be taken to interpret results and properly translate animal findings to medicine.

Carrageenan hydrogel as a scaffold for skin-derived multipotent stromal cells delivery.

Carrageenan is a thermoreversible polymer of natural origin widely used in food and pharmaceutical industry that presents a glycosaminoglycan-like structure. Herein, we show that kappa-type carrageenan extracted by a semi-refined process from the red seaweed Kappaphycus alvarezii displayed both chemical and structural properties similar to a commercial carrageenan. Moreover, both extracted carrageenan hydrogel and commercial carrageenan hydrogel can serve as a scaffold for in vitro culture of human skin-derived multipotent stromal cells, demonstrating considerable potential as cell-carrier materials for cell delivery in tissue engineering. Skin-derived multipotent stromal cells cultured inside the carrageenan hydrogels showed a round shape morphology and maintained their growth and viability for at least one week in culture. Next, the effect of the extracted carrageenan hydrogel loaded with human skin-derived multipotent stromal cells was evaluated in a mouse model of full-thickness skin wound. Macroscopic and histological analyses revealed some pointed ameliorated features, such as reduced inflammatory process, faster initial recovery of wounded area, and improved extracellular matrix deposition. These results indicate that extracted carrageenan hydrogel can serve as a scaffold for in vitro growth and maintenance of human SD-MSCs, being also able to act as a delivery system of cells to wounded skin. Thus, evaluation of the properties discussed in this study contribute to a further understanding and specificities of the potential use of carrageenan hydrogel as a delivery system for several applications, further to skin wound healing.

FGF8 and Shh promote the survival and maintenance of multipotent neural crest progenitors.

The developmental mechanisms that control the building of the complex head of vertebrates and particularly, facial skeletogenesis, remain poorly known. Progenitor cells derived from the embryonic neural crest (NC) are the major constituents and players of facial tissue development. Deciphering the cellular and molecular machinery that controls NC cell (NCC) differentiation into bone, cartilage, fat and other mesenchymal tissues, is thus a main issue for understanding vertebrate facial variations. In this work, we investigated the effects of fibroblast growth factor 8 (FGF8) and Sonic Hedgehog (Shh), two signaling molecules essential for craniofacial development, on the in vitro differentiation and multipotentiality of mesencephalic NCCs (MNCCs) isolated from the quail embryo. Comparison of distinct temporal treatments with FGF8 and/or Shh showed that both promoted chondrogenesis of MNCCs by increasing the amount and size of cartilage nodules. Higher rates of chondrogenesis were observed when MNCCs were treated with FGF8 during the migration phase, thus mimicking the in vivo exposure of migrating NCCs to FGF8 secreted by the isthmic brain signaling center. An in vitro cell cloning assay revealed that, after concomitant treatment with FGF8 and Shh, about 80% of NC progenitors displayed chondrogenic potential, while in untreated cultures, only 18% exhibited this potential. In addition, colony analysis showed for the first time the existence of a highly multipotent progenitor able to clonally give rise to adipocytes in addition to other cephalic NC phenotypes (i.e. glial cells, neurons, melanocytes, smooth muscle cells and chondrocytes) (GNMFCA progenitor). This progenitor was observed only when clonal cultures were treated with both FGF8 and Shh. Several other types of multipotent cells, which generated four, five or six distinct phenotypes, accounted for 55% of the progenitors in FGF8 and Shh treated cultures, versus 13,5% in the untreated ones. Together, these data reveal an essential role for both FGF8 and Shh together in maintenance of MNCC multipotentiality by favoring the development of NC progenitors endowed with a broad array of mesectodermal potentials.

Latin American contributions to the neural crest field.

The neural crest (NC) is one of the most fascinating structures during embryonic development. Unique to vertebrate embryos, these cells give rise to important components of the craniofacial skeleton, such as the jaws and skull, as well as melanocytes and ganglia of the peripheral nervous system. Worldwide, several groups have been studying NC development and specifically in the Latin America (LA) they have been growing in numbers since the 1990s. It is important for the world to recognize the contributions of LA researchers on the knowledge of NC development, as it can stimulate networking and improvement in the field. We developed a database of LA publications on NC development using ORCID and PUBMED as search engines. We thoroughly describe all of the contributions from LA, collected in five major topics on NC development mechanisms: i) induction and specification; ii) migration; iii) differentiation; iv) adult NC; and, v) neurocristopathies. Further analysis was done to correlate each LA country with topics and animal models, and to access collaboration between LA countries. We observed that some LA countries have made important contributions to the comprehension of NC development. Interestingly, some LA countries have a topic and an animal model as their strength; in addition, collaboration between LA countries is almost inexistent. This review will help LA NC research to be acknowledged, and to facilitate networking between students and researchers worldwide.

Bentonite modified with zinc enhances aflatoxin B1 adsorption and increase survival of fibroblasts (3T3) and epithelial colorectal adenocarcinoma cells (Caco-2).

Bentonites are commonly used as feed additives to reduce the bioavailability and thus the toxicity of aflatoxins by adsorbing the toxins in the gastrointestinal tract. Aflatoxins are particular harmful mycotoxins mainly found in areas with hot and humid climates. They occur in food and feedstuff as a result of fungal contamination before and after harvest. The aim of this study was to modify Brazilian bentonite clay by incorporation of zinc (Zn) ions in order to increase the adsorption capacity and consequently reduce the toxicity of aflatoxins. The significance of Zn intercalating conditions such as concentration, temperature and reaction time were investigated. Our results showed that the Zn treatment of the bentonite increased the aflatoxin B1 (AFB1) adsorption and that Zn concentration had a negative effect. Indeed, temperature and time had no significant effect in the binding capacity. The modified bentonite (Zn-Bent1) was not cytotoxic to either fibroblasts (3T3) nor epithelial colorectal adenocarcinoma cells (Caco-2) cell lines. Interestingly, Zn-Bent1 has higher protective effect against AFB1 induced cytotoxicity than the unmodified bentonite. In conclusion, the Zn modified bentonite, Zn-Bent1, represent an improved tool to prevent aflatoxicosis in animals fed on AFB1 contaminated feed.

Effects of Folic Acid and Homocysteine on the Morphogenesis of Mouse Cephalic Neural Crest Cells In Vitro.

Folate deficiency and hyperhomocysteinemia have long been associated with developmental anomalies, particularly neural tube defects and neurocristopathies-a group of diverse disorders that result from defective growth, differentiation, and migration of neural crest (NC) cells. However, the exact mechanisms by which homocysteine (Hcys) and/or folate deficiencies disrupt NC development are still poorly understood in mammals. In this work, we employed a well-defined culture system to investigate the effects of Hcys and folic acid (FA) supplementation on the morphogenetic processes of murine NC cells in vitro. We demonstrated that Hcys increases outgrowth and proliferation of cephalic NC cells and impairs their differentiation into smooth muscle cells. In addition, we showed that FA alone does not directly affect the developmental dynamics of the cephalic NC cells but is able to prevent the Hcys-induced effects. Our results, therefore, suggest that elevated Hcys levels per se cause dysmorphogenesis of the cephalic NC and might contribute to neurocristopathies in mammalian embryos.

Transplantation of Human Skin-Derived Mesenchymal Stromal Cells Improves Locomotor Recovery After Spinal Cord Injury in Rats.

Spinal cord injury (SCI) is a devastating neurologic disorder with significant impacts on quality of life, life expectancy, and economic burden. Although there are no fully restorative treatments yet available, several animal and small-scale clinical studies have highlighted the therapeutic potential of cellular interventions for SCI. Mesenchymal stem cells (MSCs)-which are conventionally isolated from the bone marrow-recently emerged as promising candidates for treating SCI and have been shown to provide trophic support, ameliorate inflammatory responses, and reduce cell death following the mechanical trauma. Here we evaluated the human skin as an alternative source of adult MSCs suitable for autologous cell transplantation strategies for SCI. We showed that human skin-derived MSCs (hSD-MSCs) express a range of neural markers under standard culture conditions and are able to survive and respond to neurogenic stimulation in vitro. In addition, using histological analysis and behavioral assessment, we demonstrated as a proof-of-principle that hSD-MSC transplantation reduces the severity of tissue loss and facilitates locomotor recovery in a rat model of SCI. Altogether, the study provides further characterization of skin-derived MSC cultures and indicates that the human skin may represent an attractive source for cell-based therapies for SCI and other neurological disorders. Further investigation is needed to elucidate the mechanisms by which hSD-MSCs elicit tissue repair and/or locomotor recovery.

Organophilic treatments of bentonite increase the adsorption of aflatoxin B1 and protect stem cells against cellular damage.

Bentonite clays exhibit high adsorptive capacity for contaminants, including aflatoxin B1 (AFB1), a mycotoxin responsible for causing severe toxicity in several species including pigs, poultry and man. Organophilic treatments is known to increase the adsorption capacity of bentonites, and the primary aim of this study was to evaluate the ability of Brazilian bentonite and two organic salts - benzalkonium chloride (BAC) and cetyltrimethylammonium bromide (CTAB) to adsorb AFB1. For this end, 2(2) factorial designs were used in order to analyze if BAC or CTAB was able to increase AFB1 adsorption when submitted in different temperature and concentration. Both BAC and CTAB treatment (at 30°C and 2% of salt concentration) were found to increase the adsorption of AFB1 significantly compared with untreated bentonite. After organophilic bentonite treatments with BAC or CTAB, a vibration of CH stretch (2850 and 2920cm(-1)) were detected. A frequency of the SiO stretch (1020 and 1090cm(-1)) was changed by intercalation of organic cation. Furthermore, the interlayer spacing of bentonite increases to 1.23nm (d001 reflection at 2θ=7.16) and 1.22 (d001 reflection at 2θ=7.22) after the addition of BAC and CTAB, respectively. Another aim of the study was to observe the effects of these two bentonite salts in neural crest stem cell cultures. The two materials that were created by organophilic treatments were not found to be toxic to stem cells. Furthermore the results indicate that the two materials tested may protect the neural crest stem cells against damage caused by AFB1.

Temporo-spatial analysis of Osterix, HNK1 and Sox10 during odontogenesis and maxillaries osteogenesis.

Cell differentiation is essential for maxillaries and tooth development. Facial mesenchymal tissue is formed by neural crest cells (NC). These cells are highly migratory, giving rise to various cell types, considered with a high level of plasticity, indicating that they contain progenitor cells with a great power of differentiation. In this study, it was analyzed the presence of NC cell progenitors and mesenchymal stem cells (MSC) during maxillaries osteogenesis and odontogenesis in rats. Histological slides were collected in two phases: embryonic age of 15 and 17 days; 2, 4 and 7 days after birth. Immunohistochemistry for MSC markers (Osterix) and NC cells (Sox10, HNK1) was performed. The results showed positive expression for Osterix and HNK1 in undifferentiated ectomesenchymal cells in early and late stages; Sox10 was present only in early stages in undifferentiated cells. All markers were present in differentiated cells. Although the experiments performed do not allow us to explain a possible role for Osx, HNK1 and Sox10 in both differentiated and undifferentiated cells during osteogenesis and odontogenesis, it had shown important results not yet described: the presence of HNK1 and Sox10 in osteoblasts and odontoblasts in late development stages and in the tooth germ epithelial cells and ameloblasts.

Thermal treatment of bentonite reduces aflatoxin b1 adsorption and affects stem cell death.

Bentonites are clays that highly adsorb aflatoxin B1 (AFB1) and, therefore, protect human and animal cells from damage. We have recently demonstrated that bentonite protects the neural crest (NC) stem cells from the toxicity of AFB1. Its protective effects are due to the physico-chemical properties and chemical composition altered by heat treatment. The aim of this study is to prepare and characterize the natural and thermal treatments (125 to 1000 °C) of bentonite from Criciúma, Santa Catarina, Brazil and to investigate their effects in the AFB1 adsorption and in NC cell viability after challenging with AFB1. The displacement of water and mineralogical phases transformations were observed after the thermal treatments. Kaolinite disappeared at 500 °C and muscovite and montmorillonite at 1000 °C. Slight changes in morphology, chemical composition, and density of bentonite were observed. The adsorptive capacity of the bentonite particles progressively reduced with the increase in temperature. The observed alterations in the structure of bentonite suggest that the heat treatments influence its interlayer distance and also its adsorptive capacity. Therefore, bentonite, even after the thermal treatment (125 to 1000 °C), is able to increase the viability of NC stem cells previously treated with AFB1. Our results demonstrate the effectiveness of bentonite in preventing the toxic effects of AFB1.