Human adipose tissue-derived stem cells cultured in xeno-free culture condition enhance c-MYC expression increasing proliferation but bypassing spontaneous cell transformation

Global Research Trends in Adipose Stem Cell Tissue Engineering: A Scientometric Research

Adipose Stem Cell Tissue Engineering (ASCTE) has emerged as a promising field of research in recent years. To gain comprehensive insights into this field, we conducted a comprehensive bibliometric analysis using Web of Science Core Collection and various bibliometric tools, including CiteSpace, VOS viewer, and R-Bibliometrix. Our analysis focuses on the historical development and evolution of active topics in ASCTE from a time-dynamics perspective, covering 4522 publications, 3924 academic institutions, and 873 journals, with significant growth observed over the past two decades. In terms of the global research landscape, the United States and China dominate the field. Shanghai Jiao Tong University, the University of Pittsburgh, and Ming Ho University are the top three institutions contributing to research in this area. Biomaterials is identified as the central journal in terms of cocitation analysis. Our analysis also reveals new areas of development, such as 3D printing, platelet lysate, and clinical practice, as well as current trends in hydrogels, nanomaterials, and extracellular vesicles. These findings point to exciting prospects for future ASCTE research. Unlike previous subjective reviews, our bibliometric analysis provides an objective assessment of the current state and emerging trends in ASCTE research, allowing researchers to identify popular research areas and explore new directions in this dynamic field.

Regulation of self-renewal and senescence in primitive mesenchymal stem cells by Wnt and TGFβ signaling

BACKGROUND

The therapeutic application of multipotent mesenchymal stem cells (MSCs) encounters significant challenges, primarily stemming from their inadequate growth and limited self-renewal capabilities. Additionally, as MSCs are propagated, their ability to self-renew declines, and the exact cellular and molecular changes responsible for this are poorly understood. This study aims to uncover the complex molecular mechanisms that govern the self-renewal of primitive (p) MSCs.

METHODS

We grew pMSCs using two types of medium, fetal bovine serum (FM) and xeno-free (XM), at both low passage (LP, P3) and high passage (HP, P20). To evaluate LP and HP pMSCs, we examined their physical characteristics, cell surface markers, growth rate, colony-forming ability, BrdU assays for proliferation, telomerase activity, and potential to differentiate into three lineages. Moreover, we conducted RNA-seq to analyze their transcriptome and MNase-seq analysis to investigate nucleosome occupancies.

RESULTS

When grown in FM, pMSCs underwent changes in their cellular morphology, becoming larger and elongated. This was accompanied by a decrease in the expression of CD90 and CD49f, as well as a reduction in CFE, proliferation rate, and telomerase activity. In addition, these cells showed an increased tendency to differentiate into the adipogenic lineage. However, when grown in XM, pMSCs maintained their self-renewal capacity and ability to differentiate into multiple lineages while preserving their fibroblastoid morphology. Transcriptomic analysis showed an upregulation of genes associated with self-renewal, cell cycle regulation, and DNA replication in XM-cultured pMSCs, while senescence-related genes were upregulated in FM-cultured cells. Further analysis demonstrated differential nucleosomal occupancies in self-renewal and senescence-related genes for pMSCs grown in XM and FM, respectively. These findings were confirmed by qRT-PCR analysis, which revealed alterations in the expression of genes related to self-renewal, cell cycle regulation, DNA replication, differentiation, and senescence. To understand the underlying mechanisms, we investigated the involvement of Wnt and TGFβ signaling pathways by modulating them with agonists and antagonists. This experimental manipulation led to the upregulation and downregulation of self-renewal genes in pMSCs, providing further insights into the signaling pathways governing the self-renewal and senescence of pMSCs.

CONCLUSION

Our study shows that the self-renewal potential of pMSCs is associated with the Wnt pathway, while senescence is linked to TGFβ.

WNT and VEGF/PDGF signaling regulate self-renewal in primitive mesenchymal stem cells

Background

Therapeutic use of multipotent mesenchymal stem cells (MSCs) is hampered due to poor growth and limited self-renewal potential. The self-renewal potential of MSCs is also affected during propagation and changes are poorly understood. This study investigated the molecular mechanism involved in the self-renewal of primitive (p) MSCs.

Methods

pMSCs were cultured to low passage (LP), P3, and high passage (HP), P20, in fetal bovine serum medium (FM) and xeno-free medium (XM). The characteristics of LP and HP pMSCs were evaluated for morphology, expression of cell surface markers, doubling time (DT), colony forming efficiency (CFE), proliferation by BrdU assay, telomerase activity and trilineage differentiation. We then examined transcriptome and nucleosome occupancies using RNA-seq and MNase-seq, respectively analyses.

Results

pMSCs grown in FM gradually changed morphology to large elongated cells and showed a significant reduction in the expression of CD90 and CD49f, CFE, proliferation, and telomerase activity. In addition, cells had a greater propensity to differentiate into the adipogenic lineage. In contrast, pMSCs grown in XM maintained small fibroblastoid morphology, self-renewal, and differentiation potential. Transcriptomic analysis showed upregulation of genes involved in self-renewal, cell cycle, and DNA replication in XM-grown pMSCs. Whereas senescence genes were upregulated in cells in FM. MNase-seq analysis revealed less nucleosomal occupancies in self-renewal genes and senescence genes in pMSCs grown in XM and FM, respectively. The expression of selected genes associated with self-renewal, cell cycle, DNA replication, differentiation, and senescence was confirmed by qRT-PCR. These results led us to propose signaling pathways involved in the self-renewal and senescence of pMSCs.

Conclusion

We conclude that the self-renewal potential of pMSCs is controlled by WNT and VEGF/PDGF, but TGFβ and PI3K signaling induce senescence.

Transcription Factors STAT3 and MYC Are Key Players of Human Platelet Lysate-Induced Cell Proliferation

Human platelet lysate (HPL) is an efficient alternative for animal serum supplements, significantly enhancing stromal cell proliferation. However, the molecular mechanism behind this growth-promoting effect remains elusive. The aim of this study was to investigate the effect of HPL on cell cycle gene expression in different human stromal cells and to identify the main key players that mediate HPL's growth-enhancing effect. RT-qPCR and an antibody array revealed significant upregulation of cell cycle genes in stromal cells cultured in HPL. As HPL is rich in growth factors that are ligands of tyrosine kinase receptor (TKR) pathways, we used TKR inhibitors and could significantly reduce cell proliferation. Genome profiling, RT-qPCR and Western blotting revealed an enhanced expression of the transcription factors signal transducer and activator of transcription 3 (STAT3) and MYC, both known TKR downstream effectors and stimulators of cell proliferation, in response to HPL. In addition, specifically blocking STAT3 resulted in reduced cell proliferation and expression of cell cycle genes. Our data indicate that HPL-enhanced cell proliferation can, at least in part, be explained by the TKR-enhanced expression of STAT3 and MYC, which in turn induce the expression of genes being involved in the promotion and control of the cell cycle.

Comparison of Selected Non-Coding RNAs and Gene Expression Profiles between Common Osteosarcoma Cell Lines

Simple Summary

Osteosarcoma (OS) is a malignant tumour affecting mainly children and elderly people. Despite significant advances in cancer medicine, osteosarcoma patients’ survival is not improving. The primary treatment methods are established using in vitro models that rely upon the application of well-established cell lines, including U-2 OS, Saos-2 and MG-63. The molecular phenotype of these cell lines is still not fully outlined. Therefore, our study aimed to establish the expression profile of molecular markers related to osteosarcoma survival, progression and metastasis. Non-bone-related cells were used as a reference, i.e. HeLa cell line and human adipose-derived stromal cells (hASCs). Evaluated osteosarcoma cell lines showed characteristic phenotypes with unique patterns related to upregulation of MMP-7, MMP-14, BMP-7, miR-21-5p, miR-124-3p and downregulation of lncRNA MEG3. Our findings may facilitate the selection of the most reliable cellular model for pre-clinical investigations focused on developing new and satisfying methods of osteosarcoma therapy.

Abstract

Osteosarcoma (OS) is a bone tumour affecting adolescents and elderly people. Unfortunately, basic treatment methods are still underdeveloped, which has a high impact on the poor survivability of the patients. Studies designed to understand the underlying mechanisms of osteosarcoma development, as well as preclinical investigations aimed at establishing novel therapeutic strategies, rely significantly upon in vitro models, which apply well-established cell lines such as U-2 OS, Saos-2 and MG-63. In this study, the expression of chosen markers associated with tumour progression, metastasis and survival were identified using RT-qPCR. Levels of several onco-miRs (miR-21-5p, miR-124-3p, miR-223-3p and miR-320a-3p) and long non-coding RNA MEG3 were established. The mRNA expression of bone morphogenetic proteins (BMPs), including BMP-2, BMP-3, BMP-4, BMP-6, BMP-7, as well as their receptors: BMPR-IA, BMPR-IB and BMPR-II was also determined. Other tested markers included metalloproteinases, i.e., MMP-7 and MMP-14 and survivin (BIRC5), C-MYC, as well as CYCLIN D (CCND1). The analysis included comparing obtained profiles with transcript levels established for the osteogenic HeLa cell line and human adipose-derived stromal cells (hASCs). The tested OS cell lines were characterised by a cancer-related phenotype, such as increased expression of mRNA for BMP-7, as well as MMP-7 and MMP-14. Osteosarcoma cells differ considerably in miR-21-5p and miR-124-3p levels, which can be related to uncontrolled tumour growth. The comprehensive examination of osteosarcoma transcriptome profiles may facilitate the selection of appropriate cell models for preclinical investigations aimed at the development of new strategies for OS treatment.

Enhancing therapeutic efficacy of human adipose-derived stem cells by modulating photoreceptor expression for advanced wound healing

Background

Human adipose-derived stem cells (hADSCs) have been widely used for regenerative medicine because of their therapeutic efficacy and differentiation capacity. However, there are still limitations to use them intactly due to some difficulties such as poor cell engraftment and viability after cell transplantation. Therefore, techniques such as photobiomodulation (PBM) are required to overcome these limitations. This study probed improved preclinical efficacy of irradiated hADSCs and its underlying molecular mechanism.

Methods

hADSCs were irradiated with green organic light-emitting diodes (OLEDs). Treated cells were analyzed for mechanism identification and tissue regeneration ability verification. Expression levels of genes and proteins associated with photoreceptor, cell proliferation, migration, adhesion, and wound healing were evaluated by performing multiple assays and immunostaining. Excision wound models were employed to test in vivo therapeutic effects.

Results

In vitro assessments showed that Opsin3 (OPN3) and OPN4 are both expressed in hADSCs. However, only OPN4 was stimulated by green OLED irradiation. Cell proliferation, migration, adhesion, and growth factor expression in treated hADSCs were enhanced compared to control group. Conditioned medium containing paracrine factors secreted from irradiated hADSCs increased proliferation of human dermal fibroblasts and normal human epidermal keratinocytes. Irradiated hADSCs exerted better wound healing efficacy in vivo than hADSCs without OLED irradiation.

Conclusions

Our study introduces an intracellular mechanism of PBM in hADSCs. Our results revealed that photoreceptor OPN4 known to activate G_q-protein and consequently lead to reactive oxygen species production responded to OLED irradiation with a wavelength peak of 532 nm. In conclusion, green OLED irradiation can promote wound healing capability of hADSCs, suggesting that green OLED has potential preclinical applications.

Hydrogel supplemented with human platelet lysate enhances multi-lineage differentiation of mesenchymal stem cells

Stem cells from human exfoliated deciduous teeth (SHED) can be used as a potential clinical material. But the use of xenogeneic ingredients will increase the risk of zoonotic disease transmission. Human platelet lysate (HPL) is a potential surrogate and used in human cell expansion with reliability in clinical applications. In this study, we synthesized chitosan/gelatin/gellan gum hydrogel supplemented with HPL and investigated the effect of 3D culture for SHED. TMT-tagged proteomics was used to decipher the secretome protein profiles of SHEDs and a total of 3209 proteins were identified, of which 23 were up-regulated and 192 were down-regulated. The results showed that hydrogel supplemented with HPL promoted SHED proliferation. After induction, the hydrogel coating contributed to osteogenic differentiation, adipogenic differentiation and differentiation into neural-like cells of SHED. SHED encapsulated in a hydrogel promotes migration and angiogenesis of HUVEC. In conclusion, our research found that hydrogel supplemented with HPL can be used as a method for SHED in standardized production and can contribute to the clinical application of SHED in cell therapy.

Induction of Corneal Epithelial Differentiation of Induced Pluripotent and Orbital Fat-Derived Stem Cells Seeded on Decellularized Human Corneas

Up to 40% of donor corneas are deemed unsuitable for transplantation, aggravating the shortage of graft tissue. In most cases, the corneal extracellular matrix is intact. Therefore, their decellularization followed by repopulation with autologous cells may constitute an efficient alternative to reduce the amount of discarded tissue and the risk of immune rejection after transplantation. Although induced pluripotent (hiPSCs) and orbital fat-derived stem cells (OFSCs) hold great promise for corneal epithelial (CE) reconstruction, no study to date has evaluated the capacity of decellularized corneas (DCs) to support the attachment and differentiation of these cells into CE-like cells. Here, we recellularize DCs with hiPSCs and OFSCs and evaluate their differentiation potential into CE-like cells using animal serum-free culture conditions. Cell viability and adhesion on DCs were assessed by calcein-AM staining and scanning electron microscopy. Cell differentiation was evaluated by RT-qPCR and immunofluorescence analyses. DCs successfully supported the adhesion and survival of hiPSCs and OFSCs. The OFSCs cultured under differentiation conditions could not express the CE markers, TP63, KRT3, PAX6, and KRT12, while the hiPSCs gave rise to cells expressing high levels of these markers. RT-qPCR data suggested that the DCs provided an inductive environment for CE differentiation of hiPSCs, supporting the expression of PAX6 and KRT12 without the need for any soluble induction factors. Our results open the avenue for future studies regarding the in vivo effects of DCs as carriers for autologous cell transplantation for ocular surface reconstruction.

Optimization of human umbilical cord blood-derived mesenchymal stem cell isolation and culture methods in serum- and xeno-free conditions

BACKGROUND

Although umbilical cord blood (UCB) is identified as a source of mesenchymal stem cells (MSCs) with various advantages, the success in cell isolation is volatile. Therefore, it is necessary to optimize methods of cord blood-derived MSC (UCB-MSC) isolation and culture. In this study, we evaluated the efficiency of UCB-MSC isolation and expansion using different commercially available serum- and xeno-free media and investigated the capacity of autologous serum and plasma as a supplement to support cell proliferation. Additionally, we defined the presence of multilineage-differentiating stress-enduring (Muse) cells in the UCB-MSC population. Functions of UCB-MSC in in vitro angiogenesis processes and anti-cancer were also verified.

METHODS

Mononuclear cells were isolated using density gradient separation and cultured in four commercial media kits, as well as four surface coating solutions. UCB-MSCs were characterized and tested on tube formation assay, and co-cultured with SK-MEL cells in a transwell system.

RESULTS

The results showed that only StemMACS™ MSC Expansion Media is more appropriate to isolate and culture UCB-MSCs. The cells exhibited a high cell proliferation rate, CFU forming capability, MSC surface marker expression, trilineage differentiate potential, and chromosome stability. In addition, the culture conditions with autologous serum coating and autologous plasma supplement enhanced cell growth and colony forming. This cell population contained Muse cells at rate of 0.3%. Moreover, UCB-MSCs could induce the tube formation of human umbilical vein endothelial cells and inhibit more than 50% of SK-MEL cell growth.

CONCLUSIONS

UCB-MSCs could be high-yield isolated and expanded under serum- and xeno-free conditions by using the StemMACS™ MSC Expansion Media kit. Autologous serum coating and plasma supplement enhanced cell proliferation. These UCB-MSCs had effected the tube formation process and an anti-cancer impact.

lncRNA-KCNQ1OT1: A Potential Target in Exosomes Derived from Adipose-Derived Stem Cells for the Treatment of Osteoporosis

BACKGROUND

Osteoporosis is a worldwide medical and socioeconomic burden characterized by systemic impairment of bone strength and microstructure. Exosomes derived from adipose-derived stem cells (ADSCs-Exos) have been confirmed to play effective roles in the repair of various tissues and organs. This study was aimed at investigating the role of ADSCs-Exos and a novel long noncoding RNA KCNQ1OT1 played in osteoporosis as well as the underlying mechanism.

METHODS

Primary osteoblasts were treated with different doses of tumor necrosis factor-α (TNF-α) (0, 1, 2.5, 5, and 10 ng/ml) and then cocultured with ADSCs-Exos or exosome-derived from lnc-KCNQ1OT1-modified ADSCs (KCNQ1OT1-Exos). The expression of miRNA-141-5p (miR-141-5p) and lnc-KCNQ1OT1 was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of cleaved-caspase-3, caspase-3, and Bax was determined by Western blot. Cell viability and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) and flow cytometry analysis, respectively. The binding sites between KCNQ1OT1 and miR-141-5p were validated by dual-luciferase reporter assay.

RESULTS

TNF-α dose-dependently increased miR-141-5p expression, inhibited viability, and promoted apoptosis of osteoblasts. However, miR-141-5p silencing or cocultured with ADSCs-Exos attenuated these effects. In addition, KCNQ1OT1-Exos could more significantly attenuate the induced cytotoxicity and apoptosis compared to ADSCs-Exos. Moreover, miR-141-5p was confirmed as the target of KCNQ1OT1 by luciferase reporter assay.

CONCLUSIONS

ADSCs-Exos can attenuate cytotoxicity and apoptosis of TNF-α-induced primary osteoblasts. KCNQ1OT1-Exos have a more significant inhibitory effect compared to ADSCs-Exos by the function of sponging miR-141-5p, suggesting that KCNQ1OT1-Exos can be promising agents in osteoporosis treatment.

Mesenchymal Stromal Cells from Different Parts of Umbilical Cord: Approach to Comparison & Characteristics

Mesenchymal stromal/stem cells (MSCs) are a unique population of cells that play an important role in the regeneration potential of the body. MSCs exhibit a characteristic phenotype and are capable of modulating the immune response. MSCs can be isolated from various tissues such as: bone marrow, adipose tissue, placenta, umbilical cord and others. The umbilical cord as a source of MSCs, has strong advantages, such as no-risk procedure of tissue retrieval after birth and easiness of the MSCs isolation. As the umbilical cord (UC) is a complex organ and we decided to evaluate, whether the cells derived from different regions of umbilical cord show similar or distinct properties. In this study we characterized and compared MSCs from three regions of the umbilical cord: Wharton's Jelly (WJ), the perivascular space (PRV) and the umbilical membrane (UCM). The analysis was carried out in terms of morphology, phenotype, immunomodulation potential and secretome. Based on the obtained results, we were able to conclude, that MSCs derived from distinct UC regions differ in their properties. According to our result WJ-MSCs have high and stabile proliferation potential and phenotype, when compare with other MSCs and can be treated as a preferable source of cells for medical application.

Human Platelet Lysate Acts Synergistically With Laminin to Improve the Neurotrophic Effect of Human Adipose-Derived Stem Cells on Primary Neurons in vitro

Background

Despite the advancements in microsurgical techniques and noteworthy research in the last decade, peripheral nerve lesions have still weak functional outcomes in current clinical practice. However, cell transplantation of human adipose-derived stem cells (hADSC) in a bioengineered conduit has shown promising results in animal studies. Human platelet lysate (hPL) has been adopted to avoid fetal bovine serum (FBS) in consideration of the biosafety concerns inherent with the use of animal-derived products in tissue processing and cell culture steps for translational purposes. In this work, we investigate how the interplay between hPL-expanded hADSC (hADSC^hPL) and extracellular matrix (ECM) proteins influences key elements of nerve regeneration.

Methods

hADSC were seeded on different ECM coatings (laminin, LN; fibronectin, FN) in hPL (or FBS)-supplemented medium and co-cultured with primary dorsal root ganglion (DRG) to establish the intrinsic effects of cell–ECM contact on neural outgrowth. Co-cultures were performed “direct,” where neural cells were seeded in contact with hADSC expanded on ECM-coated substrates (contact effect), or “indirect,” where DRG was treated with their conditioned medium (secretome effect). Brain-derived nerve factor (BDNF) levels were quantified. Tissue culture plastic (TCPS) was used as the control substrate in all the experiments.

Results

hPL as supplement alone did not promote higher neurite elongation than FBS when combined with DRG on ECM substrates. However, in the presence of hADSC, hPL could dramatically enhance the stem cell effect with increased DRG neurite outgrowth when compared with FBS conditions, regardless of the ECM coating (in both indirect and direct co-cultures). The role of ECM substrates in influencing neurite outgrowth was less evident in the FBS conditions, while it was significantly amplified in the presence of hPL, showing better neural elongation in LN conditions when compared with FN and TCPS. Concerning hADSC growth factor secretion, ELISA showed significantly higher concentrations of BDNF when cells were expanded in hPL compared with FBS-added medium, without significant differences between cells cultured on the different ECM substrates.

Conclusion

The data suggest how hADSC grown on LN and supplemented with hPL could be active and prone to support neuron–matrix interactions. hPL enhanced hADSC effects by increasing both proliferation and neurotrophic properties, including BDNF release.

Influences of Xeno-Free Media on Mesenchymal Stem Cell Expansion for Clinical Application

Mesenchymal stem/stromal cells (MSCs) are multipotent somatic stem/progenitor cells that can be isolated from various tissues and have attracted increasing attention from the scientific community. This is due to MSCs showing great potential for incurable disease treatment, and most applications of MSCs involve tissue degeneration and treatment of immune- and inflammation-mediated diseases. Conventional MSC cultures contain fetal bovine serum (FBS), which is a common supplement for cell development but is also a risk factor for exposure to animal-derived pathogens. To avoid the risks resulting from the xenogeneic origin and animal-derived pathogens of FBS, xeno-free media have been developed and commercialized to satisfy MSC expansion demands for human clinical applications. This review summarized and provided an overview of xeno-free media that are currently used for MSC expansion. Additionally, we discussed the influences of different xeno-free media on MSC biology with particular regard to cell morphology, surface marker expression, proliferation, differentiation and immunomodulation. The xeno-free media can be serum-free and xeno-free media or media supplemented with some human-originating substances, such as human serum, human platelet lysates, human umbilical cord serum/plasma, or human plasma-derived supplements for cell culture medium. These media have capacity to maintain a spindle-shaped morphology, the expression of typical surface markers, and the capacity of multipotent differentiation and immunomodulation of MSCs. Xeno-free media showed potential for safe use for human clinical treatment. However, the influences of these xeno-free media on MSCs are various and any xeno-free medium should be examined prior to being used for MSC cultures.

Human platelet lysate as a potential clinical-translatable supplement to support the neurotrophic properties of human adipose-derived stem cells

Background

The autologous nerve graft, despite its donor site morbidity and unpredictable functional recovery, continues to be the gold standard in peripheral nerve repair. Rodent research studies have shown promising results with cell transplantation of human adipose-derived stem cells (hADSC) in a bioengineered conduit, as an alternative strategy for nerve regeneration. To achieve meaningful clinical translation, cell therapy must comply with biosafety. Cell extraction and expansion methods that use animal-derived products, including enzymatic adipose tissue dissociation and the use of fetal bovine serum (FBS) as a culture medium supplement, have the potential for transmission of zoonotic infectious and immunogenicity. Human-platelet-lysate (hPL) serum has been used in recent years in human cell expansion, showing reliability in clinical applications.

Methods

We investigated whether hADSC can be routinely isolated and cultured in a completely xenogeneic-free way (using hPL culture medium supplement and avoiding collagenase digestion) without altering their physiology and stem properties. Outcomes in terms of stem marker expression (CD105, CD90, CD73) and the osteocyte/adipocyte differentiation capacity were compared with classical collagenase digestion and FBS-supplemented hADSC expansion.

Results

We found no significant differences between the two examined extraction and culture protocols in terms of cluster differentiation (CD) marker expression and stem cell plasticity, while hADSC in hPL showed a significantly higher proliferation rate when compared with the usual FBS-added medium. Considering the important key growth factors (particularly brain-derived growth factor (BDNF)) present in hPL, we investigated a possible neurogenic commitment of hADSC when cultured with hPL. Interestingly, hADSC cultured in hPL showed a statistically higher secretion of neurotrophic factors BDNF, glial cell-derived growth factor (GDNF), and nerve-derived growth factor (NFG) than FBS-cultured cells. When cocultured in the presence of primary neurons, hADSC which had been grown under hPL supplementation, showed significantly enhanced neurotrophic properties.

Conclusions

The hPL-supplement medium could improve cell proliferation and neurotropism while maintaining stable cell properties, showing effectiveness in clinical translation and significant potential in peripheral nerve research.

Enhanced proliferative capacity of human preadipocytes achieved by an optimized cultivating method that induces transient activity of hTERT

Human mesenchymal stromal cells (MSC) are an important tool for basic and translational research. Large amounts of MSC are required for in vitro and in vivo studies, however, the limited life-span and differentiation ability in vitro hamper their optimal use. Here we report that 1:1 mixture of L15 and mTeSR1 culture media increased the life-span of IPI-SA3-C4, a normal non-immortalized human subcutaneous preadipocyte strain by 20% while retaining their adipogenic capacity and stable karyotype. The increased proliferative capacity was accompanied by increased expression of the stem markers POU5F1, SOX2, MYC and hTERT, and inhibition of hTERT activity abolished the growth advantage of L15-mTeSR1. Consequently, the described MSC culture would considerably enhance the utility of MSC for in vitro studies.

Impact of low-intensity pulsed ultrasound on transcription and metabolite compositions in proliferation and functionalization of human adipose-derived mesenchymal stromal cells

To investigate the effect of low-intensity pulsed ultrasound (LIPUS) on the proliferation of human adipose-derived mesenchymal stromal cells (hASCs) and uncovered its stimulation mechanism. LIPUS at 30 mW/cm² was applied for 5 min/day to promote the proliferation of hASCs. Flow cytometry was used to study the cell surface markers, cell cycle, and apoptosis of hASCs. The proliferation of hASCs was detected by cell counting kit-8, cell cycle assay, and RT-PCR. The expression of hASCs cytokines was determined by ELISA. The differences between transcriptional genes and metabolites were analyzed by transcript analysis and metabolomic profiling experiments. The number of cells increased after LIPUS stimulation, but there was no significant difference in cell surface markers. The results of flow cytometry, RT-PCR, and ELISA after LIPUS was administered showed that the G₁ and S phases of the cell cycle were prolonged. The expression of cell proliferation related genes (CyclinD1 and c-myc) and the paracrine function related gene (SDF-1α) were up-regulated. The expression of cytokines was increased, while the apoptosis rate was decreased. The results of transcriptome experiments showed that there were significant differences in 27 genes;15 genes were up-regulated, while 12 genes were down-regulated. The results of metabolomics experiments showed significant differences in 30 metabolites; 7 metabolites were up-regulated, and 23 metabolites were down-regulated. LIPUS at 30 mW/cm² intensity can promote the proliferation of hASCs cells in an undifferentiating state, and the stem-cell property of hASCs was maintained. CyclinD1 gene, c-myc gene, and various genes of transcription and products of metabolism play an essential role in cell proliferation. This study provides an important experimental and theoretical basis for the clinical application of LIPUS in promoting the proliferation of hASCs cells.

Epithelial basement membrane of human decellularized cornea as a suitable substrate for differentiation of embryonic stem cells into corneal epithelial-like cells

The ability to decellularize and recellularize the corneas deemed unsuitable for transplantation may increase the number of available grafts. Decellularized corneas (DCs) may provide a natural microenvironment for cell adhesion and differentiation. Despite this, no study to date has evaluated their efficacy as a substrate for the induction of stem cell differentiation into corneal cells. The present study aimed to compare the efficiency of NaCl and NaCl plus nucleases methods to decellularize whole human corneas, and to investigate the effect of epithelial basement membrane (EBM) of whole DCs on the ability of human embryonic stem cells (hESCs) to differentiate into corneal epithelial-like cells when cultured in animal serum-free differentiation medium. As laminin is the major component of EBM, we also investigated its effect on hESCs differentiation. The decellularization efficiency and integrity of the extracellular matrix (ECM) obtained were investigated by histology, electron microscopy, DNA quantification, immunofluorescence, and nuclear staining. The ability of hESCs to differentiate into corneal epithelial-like cells when seeded on the EBM of DCs or laminin-coated wells was evaluated by immunofluorescence and RT-qPCR analyses. NaCl treatment alone, without nucleases, was insufficient to remove cellular components, while NaCl plus nucleases treatment resulted in efficient decellularization and preservation of the ECM. Unlike cells induced to differentiate on laminin, hESCs differentiated on DCs expressed high levels of corneal epithelial-specific markers, keratin 3 and keratin 12. It was demonstrated for the first time that the decellularized matrices had a positive effect on the differentiation of hESCs towards corneal epithelial-like cells. Such a strategy supports the potential applications of human DCs and hESCs in corneal epithelium tissue engineering.

Neuroprotective potential of Ayahuasca and untargeted metabolomics analyses: applicability to Parkinson's disease

ETHNOPHARMACOLOGY RELEVANCE

Ayahuasca is a tea produced through decoction of Amazonian plants. It has been used for centuries by indigenous people of South America. The beverage is considered to be an ethnomedicine, and it is traditionally used for the treatment of a wide range of diseases, including neurological illness. Besides, some scientific evidence suggests it may be applicable to Parkinson's disease (PD) treatment. Thus, Ayahuasca deserves in depth studies to clarify its potential role in this disease.

AIM OF THE STUDY

This study aimed to use an untargeted metabolomics approach to evaluate the neuroprotective potential of the Ayahuasca beverage, the extracts from its matrix plants (Banisteriopsis caapi and Psychotria viridis), its fractions and its main alkaloids on the viability of SH-SY5Y neuroblastoma cells in an in vitro PD model.

MATERIAL AND METHODS

The cytotoxicity of Ayahuasca, crude extracts, and fractions of B. caapi and P. viridis, as well as neuroprotection promoted by these samples in a 6-hydroxydopamine (6-OHDA)-induced neurodegeneration model, were evaluated by the MTT assay at two time-points: 48 h (T1) and 72 h (T2). The main alkaloids from Ayahuasca matrix plants, harmine (HRE) and N,N-dimethyltryptamine (DMT), were also isolated and evaluated. An untargeted metabolomics approach was developed to explore the chemical composition of samples with neuroprotective activity. Ultra-Performance Liquid Chromatography coupled to Electrospray Ionisation and Time-of-Flight (UPLC-ESI-TOF) metabolome data was treated and further analysed using multivariate statistical analyses (MSA): principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The metabolites were dereplicated using the Dictionary of Natural Products and an in house database. The main alkaloids were also quantified by UPLC-MS/MS.

RESULTS

The samples did not cause cytotoxicity in vitro and three of samples intensely increased cell viability at T1. The crude extracts, alkaloid fractions and HRE demonstrated remarkable neuroprotective effect at T2 while the hydroalcoholic fractions demonstrated this neuroprotective effect at T1 and T2. Several compounds from different classes, such as β-carbolines and monoterpene indole alkaloids (MIAs) were revealed correlated with this property by MSA. Additionally, a total of 2419 compounds were detected in both ionisation modes. HRE showed potent neuroprotective action at 72 h, but it was not among the metabolites positively correlated with the most efficacious neuroprotective profile at either time (T1 and T2). Furthermore, DMT was statistically important to differentiate the dataset (VIP value > 1), although it did not exhibit sufficient neuroprotective activity by in vitro assay, neither a positive correlation with T1 and T2 neuroprotective profile, which corroborated the MSA results.

CONCLUSION

The lower doses of the active samples stimulated neuronal cell proliferation and/or displayed the most efficacious neuroprotection profile, namely by preventing neuronal damage and improving cell viability against 6-OHDA-induced toxicity. Intriguingly, the hydroalcoholic fractions exhibited enhanced neuroprotective effects when compared to other samples and isolated alkaloids. This finding corroborates the significance of a holistic approach. The results demonstrate that Ayahuasca and its base plants have potential applicability for PD treatment and to prevent its progression differently from current drugs to treat PD.

Ex Vivo Human Adipose Tissue Derived Mesenchymal Stromal Cells (ASC) Are a Heterogeneous Population That Demonstrate Rapid Culture-Induced Changes

Human adipose-derived mesenchymal stromal cells (ASC) are showing clinical promise for the treatment of a range of inflammatory and degenerative conditions. These lipoaspirate-derived cells are part of the abundant and accessible source of heterogeneous stromal vascular fraction (SVF). They are typically isolated and expanded from the SVF via adherent cell culture for at least 2 weeks and as such represent a relatively undefined population of cells. We isolated ex vivo ASC directly from lipoaspirate using a cocktail of antibodies combined with immunomagnetic bead sorting. This method allowed for the rapid enrichment of a defined and untouched ex vivo ASC population (referred to as MACS-derived ASC) that were then compared to culture-derived ASC. This comparison found that MACS-derived ASC contain a greater proportion of cells with activity in in vitro differentiation assays. There were also significant differences in the secretion levels of some key paracrine molecules. Moreover, when the MACS-derived ASC were subjected to adherent tissue culture, rapid changes in gene expression were observed. This indicates that culturing cells may alter the clinical utility of these cells. Although MACS-derived ASC are more defined compared to culture-derived ASC, further investigations using a comprehensive multicolor flow cytometry panel revealed that this cell population is more heterogeneous than previously appreciated. Additional studies are therefore required to more precisely delineate phenotypically distinct ASC subsets with the most therapeutic potential. This research highlights the disparity between ex vivo MACS-derived and culture-derived ASC and the need for further characterization.

Improved vascularisation but inefficient in vivo bone regeneration of adipose stem cells and poly-3-hydroxybutyrate-co-3-hydroxyvalerate scaffolds in xeno-free conditions

Bone defects are a common clinical situation. However, bone regeneration remains a challenge and faces the limitation of poor engraftment due to deficient vascularisation. Poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHB-HV) and human adipose stem cells (hASC) are promising for vascularisation and bone regeneration. Therefore, we sought to investigate the bone regenerative capacity of hASCs cultured in allogeneic human serum (aHS) and PHB-HV scaffolds in a nude mouse model of the critical-sized calvarial defect. We evaluated bone healing for three treatment groups: empty (control), PHB-HV and PHB-HV + hASCs. The pre-implant analysis showed that hASCs colonised the PHB-HV scaffolds maintaining cell viability before implantation. Histological analysis revealed that PHB-HV scaffolds were tolerated in vivo; they integrated with adjacent tissue eliciting a response like a foreign body reaction, and tiny primary bone was observed only in the PHB-HV group. Also, the μ-CT analysis revealed only approximately 10% of new bone in the bone defect area in both the PHB-HV and PHB-HV + hASCs groups. The expression of BGLAP and its protein (osteocalcin) by PHB-HV + hASCs group and native bone was similar while the other bone markers RUNX2, ALPL and COL1A1 were upregulated, but this expression remained significantly lower compared to the native bone. Nevertheless, the PHB-HV group showed neovascularisation at 12 weeks post-implantation while PHB-HV + hASCs group also exhibited higher VEGFA expression as well as a higher number of vessels at 4 weeks post-implantation, and, consequently, earlier neovascularisation. This neovascularisation must be due to scaffold architecture, improved by hASCs, that survived for the long term in vivo in the PHB-HV + hASCs group. These results demonstrated that hASCs cultured in aHS combined with PHB-HV scaffolds were ineffective to promote bone regeneration, although the construct of hASCs + PHB-HV in xeno-free conditions improved scaffold vascularisation representing a strategy potentially promising for other tissue engineering applications.

Genetic Stability of Mesenchymal Stromal Cells for Regenerative Medicine Applications: A Fundamental Biosafety Aspect

Mesenchymal stem/stromal cells (MSC) show widespread application for a variety of clinical conditions; therefore, their use necessitates continuous monitoring of their safety. The risk assessment of mesenchymal stem cell-based therapies cannot be separated from an accurate and deep knowledge of their biological properties and in vitro and in vivo behavior. One of the most relevant safety issues is represented by the genetic stability of MSCs, that can be altered during in vitro manipulation, frequently required before clinical application. MSC genetic stability has the potential to influence the transformation and the therapeutic effect of these cells. At present, karyotype evaluation represents the definitely prevailing assessment of MSC stability, but DNA alterations of smaller size should not be underestimated. This review will focus on current scientific knowledge about the genetic stability of mesenchymal stem cells. The techniques used and possible improvements together with regulatory aspects will also be discussed.

An improved method of culturing somatotropic cells from rat adenohypophysis

This study aimed to propose a simple and practical method for culturing primary rat somatotropic cells in vitro free of pericytes contamination. Rat adenohypophyses were randomly divided into two groups. An improved method was used in group A (digesting adenohypophysis with 0.25% trypsin-EDTA, followed by removing pericytes by double filtration and using serum-free medium for culturing somatotropic cells). The traditional method was used in group B (digesting adenohypophysis with 0.35% collagenase, using serum medium for culturing somatotropic cells, and removing pericytes by changing the culture dish). The numbers and viability of somatotropic cells were higher in group A than in group B after 6 days. GH secretion of somatotropic cells was also higher in group A than in group B. Besides, the pericytes grew rapidly only in group B after 3 days. α-SMA, type I collagen, and type III collagen had weaker expression in group A. Also, the viability of pericytes decreased in group A. The improved method could solve the problem of pericytes contamination, and the culture of primary rat somatotropic cells in vitro was successful. This method can be used for other primary cultures with pericytes contamination.

Survival/Adaptation of Bone Marrow-Derived Mesenchymal Stem Cells After Long-Term Starvation Through Selective Processes

After in vivo transplantation, mesenchymal stem cells (MSC) face an ischemic microenvironment, characterized by nutrient deprivation and reduced oxygen tension, which reduces their viability and thus their therapeutic potential. Therefore, MSC response to models of in vitro ischemia is of relevance for improving their survival and therapeutic efficacy. The aim of this study was to understand the survival/adaptive response mechanism that MSC use to respond to extreme culture conditions. Specifically, the effect of a long-term starvation on human bone marrow (hBM)-derived MSC cultured in a chemically defined medium (fetal bovine serum-free [SF] and human SF), either in hypoxic or normoxic conditions. We observed that hBM-MSC that were isolated and cultured in SF medium and subjected to a complete starvation for up to 75 days transiently changed their behavior and phenotype. However, at the end of that period, hBM-MSC retained their characteristics as determined by their morphology, DNA damage resistance, proliferation kinetic, and differentiation potential. This survival mode involved a quiescent state, confirmed by increased expression of cell cycle regulators p16, p27, and p57 and decreased expression of proliferating cell nuclear antigen (PCNA), Ki-67, mTOR, and Nanog. In addition, Jak/STAT (STAT6) antiapoptotic activity selected which cells conserved stemness and that supported metabolic, bioenergetic, and scavenging requirements. We also demonstrated that hBM-MSC exploited an autophagic process which induced lipid β-oxidation as an alternative energy source. Priming MSC by concomitant starvation and culture in hypoxic conditions to induce their quiescence would be of benefit to increase MSC survival when transplanted in vivo. Stem Cells 2019;37:813-827.

Impact of c-MYC expression on proliferation, differentiation, and risk of neoplastic transformation of human mesenchymal stromal cells

BACKGROUND

Mesenchymal stromal cells isolated from bone marrow (MSC) represent an attractive source of adult stem cells for regenerative medicine. However, thorough research is required into their clinical application safety issues concerning a risk of potential neoplastic degeneration in a process of MSC propagation in cell culture for therapeutic applications. Expansion protocols could preselect MSC with elevated levels of growth-promoting transcription factors with oncogenic potential, such as c-MYC. We addressed the question whether c-MYC expression affects the growth and differentiation potential of human MSC upon extensive passaging in cell culture and assessed a risk of tumorigenic transformation caused by MSC overexpressing c-MYC in vivo.

METHODS

MSC were subjected to retroviral transduction to induce expression of c-MYC, or GFP, as a control. Cells were expanded, and effects of c-MYC overexpression on osteogenesis, adipogenesis, and chondrogenesis were monitored. Ectopic bone formation properties were tested in SCID mice. A potential risk of tumorigenesis imposed by MSC with c-MYC overexpression was evaluated.

RESULTS

C-MYC levels accumulated during ex vivo passaging, and overexpression enabled the transformed MSC to significantly overgrow competing control cells in culture. C-MYC-MSC acquired enhanced biological functions of c-MYC: its increased DNA-binding activity, elevated expression of the c-MYC-binding partner MAX, and induction of antagonists P19ARF/P16INK4A. Overexpression of c-MYC stimulated MSC proliferation and reduced osteogenic, adipogenic, and chondrogenic differentiation. Surprisingly, c-MYC overexpression also caused an increased COL10A1/COL2A1 expression ratio upon chondrogenesis, suggesting a role in hypertrophic degeneration. However, the in vivo ectopic bone formation ability of c-MYC-transduced MSC remained comparable to control GFP-MSC. There was no indication of tumor growth in any tissue after transplantation of c-MYC-MSC in mice.

CONCLUSIONS

C-MYC expression promoted high proliferation rates of MSC, attenuated but not abrogated their differentiation capacity, and did not immediately lead to tumor formation in the tested in vivo mouse model. However, upregulation of MYC antagonists P19ARF/P16INK4A promoting apoptosis and senescence, as well as an observed shift towards a hypertrophic collagen phenotype and cartilage degeneration, point to lack of safety for clinical application of MSC that were manipulated to overexpress c-MYC for their better expansion.

Cytogenetic and Transcriptomic Analysis of Human Endometrial MSC Retaining Proliferative Activity after Sublethal Heat Shock

Temperature is an important exogenous factor capable of leading to irreversible processes in the vital activity of cells. However, the long-term effects of heat shock (HS) on mesenchymal stromal cells (MSC) remain unstudied. We investigated the karyotype and DNA repair drivers and pathways in the human endometrium MSC (eMSC) survived progeny at passage 6 after sublethal heat stress (sublethal heat stress survived progeny (SHS-SP)). G-banding revealed an outbreak of random karyotype instability caused by chromosome breakages and aneuploidy. Molecular karyotyping confirmed the random nature of this instability. Transcriptome analysis found homologous recombination (HR) deficiency that most likely originated from the low thermostability of the AT-rich HR driving genes. SHS-SP protection from transformation is provided presumably by low oncogene expression maintained by tight co-regulation between thermosensitive HR drivers BRCA, ATM, ATR, and RAD51 (decreasing expression after SHS), and oncogenes mTOR, MDM2, KRAS, and EGFR. The cancer-related transcriptomic features previously identified in hTERT transformed MSC in culture were not found in SHS-SP, suggesting no traits of malignancy in them. The entrance of SHS-SP into replicative senescence after 25 passages confirms their mortality and absence of transformation features. Overall, our data indicate that SHS may trigger non-tumorigenic karyotypic instability due to HR deficiency and decrease of oncogene expression in progeny of SHS-survived MSC. These data can be helpful for the development of new therapeutic approaches in personalized medicine.

Immunocytochemical analysis of valproic acid induced histone H3 and H4 acetylation during differentiation of rat adipose derived stem cells into neuron-like cells

Valproic acid (VPA) is an inhibitor of histone deacetylases (HDACs) that can regulate differentiation and proliferation of stem cells by epigenetic mechanisms. We investigated VPA induced histone H3 and H4 acetylation in adipose derived stem cells (ADSCs) transdifferentiated into neuron-like cells (NLCs). Rat ADSCs were transdifferentiated into neural stem cells (NSCs) that had been generated from neurospheres. The NSCs were differentiated into NLCs by induction with different concentrations of VPA at 24, 48 and 72 h. The NLCs were evaluated using anti-H3 and -H4 antibodies, and ADSCs, NSCs and NLCs were evaluated using immunofluorescence. The ADSCs were immunoreactive to CD90 and CD49d, but not to CD45 and CD31. Both the neurospheres and NSCs were immunostained with nestin and neurofilament 68. The neurospheres expressed Musashi1, Sox2 and Neu N genes as determined by RT-PCR. Our dose-response study indicated that the optimal concentration of VPA was 1 mM at 72 h. Histone acetylation levels of H3 and H4 immunostaining intensities in NLCs were significantly greater than for ADSCs and NSCs. VPA alters H4 and H3 acetylation immunoreactivities of ADSCs transdifferentiated into NLCs.

[Effect of human adipose-derived stem cells on pressure ulcer healing in mouse]

Objective

To investigate the effect of human adipose-derived stem cells (hADSCs) on pressure ulcers in mouse.

Methods

The subcutaneous adipose tissue from voluntary donation was harvested. Then the hADSCs were isolated and cultured by mechanical isolation combined with typeⅠcollagenase digestion. The 3rd generation cells were identified by osteogenic, adipogenic, chondrogenic differentiations and flow cytometry. The platelet rich plasma (PRP) from peripheral blood donated by healthy volunteers was prepared by centrifugation. The pressure ulcer model was established in 45 C57BL/6 mice by two magnets pressurized the back skin, and randomly divided into 3 groups ( n=15). The wounds were injected with 100 μL of hADSCs (1×10 ⁶ cells) transfected with a green fluorescent protein (GFP)-carrying virus, 100 μL human PRP, and 100 μL PBS in hADSCs group, PRP group, and control group, respectively. The wound healing was observed after injection. The wound healing rate was calculated on the 5th, 9th, and 13th days. On the 5th, 11th, and 21st day, the specimens were stained with HE staing, Masson staining, and CD31 and S100 immunohistochemical staining to observe the vascular and nerve regeneration of the wound. In hADSCs group, fluorescence tracer method was used to observe the colonization and survival of the cells on the 11th day.

Results

The cultured cells were identified as hADSCs by induced differentiation and flow cytometry. The platelet counting was significantly higher in PRP group than in normal peripheral blood group ( t=5.781, P=0.029). General observation showed that the wound healing in hADSCs group was superior to those in PRP group and control group after injection. On the 5th, 9th, and 13th days, the wound healing rate in hADSCs group was significantly higher than those in PRP group and control group ( P<0.05). Histological observation showed that compared with PRP group and control group, inflammatory cell infiltration and inflammatory reaction were significantly reduced in hADSCs group, collagen deposition was significantly increased, and skin appendage regeneration was seen on the 21st day; at each time point, the expression of collagen was significantly higher in hADSCs group than in PRP group and control group ( P<0.05). Immunohistochemical staining showed that the number of neovascularization and the percentage of S100-positive cells in hADSCs group were significantly better than those in PRP group and control group on the 5th, 9th, and 13th days ( P<0.05). Fluorescent tracer method showed that the hADSCs could colonize the wound and survive during 11 days after injection.

Conclusion

Local transplantation of hADSCs can accelerate healing of pressure ulcer wounds in mice and improve healing quality by promoting revascularization and nerve regeneration.

Improved GMP compliant approach to manipulate lipoaspirates, to cryopreserve stromal vascular fraction, and to expand adipose stem cells in xeno-free media

Background

The stromal vascular fraction (SVF) derived from adipose tissue contains adipose-derived stromal/stem cells (ASC) and can be used for regenerative applications. Thus, a validated protocol for SVF isolation, freezing, and thawing is required to manage product administration. To comply with Good Manufacturing Practice (GMP), fetal bovine serum (FBS), used to expand ASC in vitro, could be replaced by growth factors from platelet concentrates.

Methods

Throughout each protocol, GMP-compliant reagents and devices were used. SVF cells were isolated from lipoaspirates by a standardized enzymatic protocol. Cells were cryopreserved in solutions containing different albumin or serum and dimethylsulfoxide (DMSO) concentrations. Before and after cryopreservation, we analyzed: cell viability (by Trypan blue); immunophenotype (by flow cytometry); colony-forming unit-fibroblast (CFU-F) formation; and differentiation potential. ASC, seeded at different densities, were expanded in presence of 10% FBS or 5% supernatant rich in growth factors (SRGF) from platelets. The differentiation potential and cell transformation grade were tested in expanded ASC.

Results

We demonstrated that SVF can be obtained with a consistent yield (about 185 × 10³ cells/ml lipoaspirate) and viability (about 82%). Lipoaspirate manipulation after overnight storage at +4 °C reduced cell viability (−11.6%). The relative abundance of ASC (CD34⁺CD45⁻CD31^–) and endothelial precursors (CD34⁺CD45⁻CD31⁺) in the SVF product was about 59% and 42%, respectively. A period of 2 months cryostorage in autologous serum with added DMSO minimally affected post-thaw SVF cell viability as well as clonogenic and differentiation potentials. Viability was negatively affected when SVF was frozen at a cell concentration below 1.3 × 10⁶ cells/ml. Cell viability was not significantly affected after a freezing period of 1 year.

Independent of seeding density, ASC cultured in 5% SRGF exhibited higher growth rates when compared with 10% FBS. ASC expanded in both media showed unaltered identity (by flow cytometry) and were exempt from genetic lesions. Both 5% SRGF- and 10% FBS-expanded ASC efficiently differentiated to adipocytes, osteocytes, and chondrocytes.

Conclusions

This paper reports a GMP-compliant approach for freezing SVF cells isolated from adipose tissue by a standardized protocol. Moreover, an ASC expansion method in controlled culture conditions and without involvement of animal-derived additives was reported.

Molecular Genetic Analysis of Human Endometrial Mesenchymal Stem Cells That Survived Sublethal Heat Shock

High temperature is a critical environmental and personal factor. Although heat shock is a well-studied biological phenomenon, hyperthermia response of stem cells is poorly understood. Previously, we demonstrated that sublethal heat shock induced premature senescence in human endometrial mesenchymal stem cells (eMSC). This study aimed to investigate the fate of eMSC-survived sublethal heat shock (SHS) with special emphasis on their genetic stability and possible malignant transformation using methods of classic and molecular karyotyping, next-generation sequencing, and transcriptome functional analysis. G-banding revealed random chromosome breakages and aneuploidy in the SHS-treated eMSC. Molecular karyotyping found no genomic imbalance in these cells. Gene module and protein interaction network analysis of mRNA sequencing data showed that compared to untreated cells, SHS-survived progeny revealed some difference in gene expression. However, no hallmarks of cancer were found. Our data identified downregulation of oncogenic signaling, upregulation of tumor-suppressing and prosenescence signaling, induction of mismatch, and excision DNA repair. The common feature of heated eMSC is the silence of MYC, AKT1/PKB oncogenes, and hTERT telomerase. Overall, our data indicate that despite genetic instability, SHS-survived eMSC do not undergo transformation. After long-term cultivation, these cells like their unheated counterparts enter replicative senescence and die.

Venous Blood Derivatives as FBS-Substitutes for Mesenchymal Stem Cells: A Systematic Scoping Review

Although the biological properties of mesenchymal stem cells (MSC) are well-characterized in vitro, MSC clinical application is still far away to be achieved, mainly due to the need of xenogeneic substances for cell expansion, such as fetal bovine serum (FBS). FBS presents risks regarding pathogens transmissions and internalization of animal's proteins, which can unleash antigenic responses in patients after MSC implantation. A wide range of venous blood derivatives (VBD) has been reported as FBS substitutes showing promising results. Thus, the aim of this study was to conduct a systematic scoping review to analyze whether VBD are effective FBS substitutes for MSC ex vivo expansion. The search was performed in SciVerse ScopusTM, PubMed, Web of ScienceTM, BIREME, Cochrane library up to January 2016. The keywords were selected using MeSH and entry terms. Two independent reviewers scrutinized the records obtained considering specific inclusion criteria. The included studies were evaluated in accordance with a modified Arksey and O' Malley's framework. From 184 found studies, 90 were included. Bone marrow mesenchymal stem cells (BMMSC) were presented in most of these studies. Overall, VBD allowed for either, maintenance of MCS's fibroblast-like morphology, high proliferation, high colony-formation ability and maintenance of multipotency. Besides. MSC expanded in VBD supplements presented higher mitogen activity than FBS. VBD seems to be excellent xeno-free serum for ex vivo expansion of mesenchymal stem cells. However, an accentuated heterogeneity was observed between the carried out protocols for VBD isolation did not allowing for direct comparisons between the included studies.

Remodeling the Human Adult Stem Cell Niche for Regenerative Medicine Applications

The interactions between stem cells and their surrounding microenvironment are pivotal to determine tissue homeostasis and stem cell renewal or differentiation and regeneration in vivo. Ever since they were postulated in 1978, stem cell niches have been identified and characterized in many germline and adult tissues. Comprehensive studies over the last decades helped to clarify the critical components of stem cell niches that include cellular, extracellular, biochemical, molecular, and physical regulators. This knowledge has direct impact on their inherent regenerative potential. Clinical applications demand readily available cell sources that, under controlled conditions, provide a specific therapeutic function. Thus, translational medicine aims at optimizing in vitro or in vivo the various components and complex architecture of the niche to exploit its therapeutic potential. Accordingly, the objective is to recreate the natural niche microenvironment during cell therapy process development and closely comply with the requests of regulatory authorities. In this paper, we review the most recent advances of translational medicine approaches that target the adult stem cell natural niche microenvironment for regenerative medicine applications.

A human plasma derived supplement preserves function of human vascular cells in absence of fetal bovine serum

Current techniques for cell culture routinely use animal-derived components. Fetal bovine serum (FBS) is the most widely applied supplement, but it often displays significant batch-to-batch variations and is generally not suitable for clinical applications in humans. A robust and xeno-free alternative to FBS is of high interest for cellular therapies, from early in vitro testing to clinical trials in human subjects. In the current work, a highly consistent human plasma derived supplement (SCC) has been tested, as a potential substitute of FBS in primary human vascular cells culture. Our results show that SCC is able to support proliferation, preserve cellular morphology and potentiate functionality analogously to FBS. We conclude that SCC is a viable substitute of FBS for culture and expansion of cells in advanced therapies using human vascular cells and fibroblasts.

Leukocyte-Reduced Platelet-Rich Plasma Alters Protein Expression of Adipose Tissue-Derived Mesenchymal Stem Cells

BACKGROUND

Application of platelet-rich plasma and stem cells has become important in regenerative medicine. Recent literature supports the use of platelet-rich plasma as a cell culture media supplement to stimulate proliferation of adipose tissue-derived mesenchymal stem cells. The underlying mechanism of proliferation stimulation by platelet-rich plasma has not been investigated so far.

METHODS

Adipose tissue-derived mesenchymal stem cells were cultured in α-minimal essential medium supplemented with platelet-rich plasma or fetal calf serum. Cell proliferation was assessed with cell cycle kinetics using flow cytometric analyses after 48 hours. Differences in proteome expression of the adipose tissue-derived mesenchymal stem cells were analyzed using a reverse-phase protein array to quantify 214 proteins. Complementary Ingenuity Pathways Analysis and gene set enrichment analysis were performed using protein data, and confirmed by Western blot analysis.

RESULTS

A higher percentage of adipose tissue-derived mesenchymal stem cells in the S phase in the presence of platelet-rich plasma advocates the proliferation stimulation. Ingenuity Pathways Analysis and gene set enrichment analysis confirm the involvement of the selected proteins in the process of cell growth and proliferation. Ingenuity Pathways Analysis revealed a participation in the top-ranked canonical pathways PI3K/AKT, PTEN, ILK, and IGF-1. Gene set enrichment analysis identified the authors' protein set as being part of significantly regulated protein sets with the focus on cell cycle, metabolism, and the Kyoto Encyclopedia of Genes and Genomes transforming growth factor-β signaling pathway.

CONCLUSIONS

The present study provides evidence that platelet-rich plasma stimulates proliferation and induces a unique change in the proteomic profile of adipose tissue-derived mesenchymal stem cells. The interpretation of altered expression of regulatory proteins represents a step forward toward achieving good manufacturing practice-compliant criteria for cell-based strategies.

Synthetic matrix of polyether-polyurethane as a biological platform for pancreatic regeneration

AIMS

Several alternative cellular approaches using biomaterials to host insulin-producing cells derived from stem cells have been developed to overcome the limitations of type 1 diabetes treatment (exogenous insulin injection). However, none seem to fulfill all requirements needed to induce pancreatic cells successful colonization of the scaffolds. Here, we report a polymeric platform adherent to the native mice pancreas filled with human adipose stem cells (hASCs) that was able to induce growth of pancreatic parenchyma.

MAIN METHODS

Synthetic polyether-polyurethane discs were placed adjacent to pancreas of normoglycemic and streptozotocin-induced diabetic mice. At day 4 post implantation, 1×10⁶ hASCs were injected intra-implant in groups of normoglycemic and diabetic mice. Immunohistochemistry analysis of the implants was performed to identify insulin positive cells in the newly formed tissue. In addition, metabolic, inflammatory and angiogenic parameters were carried out in those mice.

KEY FINDINGS

This study provides evidence of the ability of a biohybrid device to induce the growth of differentiated pancreas parenchyma in both normoglycemic and streptozotocin-induced diabetic mice as detected by histological analysis. Glucose metabolism and body weight of hyperglycemic mice bearing hASCs implants improved.

SIGNIFICANCE

The synthetic porous scaffold bearing hASC cells placed adjacent to the native animal pancreas exhibits the potential to be exploited in future cell-based type 1 diabetes therapies.

Challenges of bone tissue engineering in orthopaedic patients

Bone defects may impede normal biomechanics and the structural stability of bone as an organ. In many cases, the correction of bone defects requires extensive surgical intervention involving the use of bone-grafting techniques and other procedures in which healing is slow, there is a high risk of infection and considerable pain is provoked - with no guarantee of complete correction of the defect. Therefore, the search for surgical alternatives continues to present a major challenge in orthopaedic traumatology. The reamer-irrigator-aspirator (RIA) system, which was devised to avoid the problems that can arise with autograft harvesting from the iliac crest, consists of collecting the product of the femoral canal after reaming. The RIA technique improves osteogenic differentiation of mesenchymal stem cells, compared to bone marrow aspiration or cancellous bone harvesting from the iliac crest using a spoon. Another approach, the Masquelet technique, consists of reconstructing a long bone defect by means of an induced membrane grown onto an acrylic cement rod inserted to fill the defect; in a second surgical step, once the membrane is constituted, the cement rod is removed and cancellous autograft is used to fill the defect. Both in RIA and in the Masquelet technique, osteosynthesis is usually needed. Bone transportation by compression-distraction lengthening principles is commonly implemented for the treatment of large bone loss. However, complications are frequently encountered with these techniques. Among new techniques that have been proposed to address the problem of large bone loss, the application of stem cells in conjunction with tissue engineering techniques is very promising, as is the creation of personalised medicine (or precision medicine), in which molecular profiling technologies are used to tailor the therapeutic strategy, to ensure the right method is applied for the right person at the right time, after determining the predisposition to disease among the general population. All of the above techniques for addressing bone defects are discussed in this paper.

Pooled Human Serum Increases Regenerative Potential of In Vitro Expanded Stem Cells from Human Extracted Deciduous Teeth

In regenerative therapy, in vitro expansion of stem cells is critical to obtain a significantly higher number of cells for successful engraftment after transplantation. However, stem cells lose its regenerative potential and enter senescence during in vitro expansion. In this study, the influence of foetal bovine serum (FBS) and pooled human serum (pHS) on the proliferation, morphology and migration of stem cells from human extracted deciduous teeth (SHED) was compared. SHED (n = 3) was expanded in KnockOut DMEM supplemented with either pHS (pHS-SM) or FBS (FBS-SM). pHS was prepared using peripheral blood serum of six healthy male adults, aged between 21 and 35 years old. The number of live SHED was significantly higher, from passage 5 to 7, when cultured in pHS-SM compared to those cultured in FBS-SM (p < 0.05). Number of cells having flattened morphology, characteristics of partially differentiated and senescent cells, was significantly lower (p < 0.05) in pHS-SM (3%) compared to those in FBS-SM (7%). Furthermore, migration of SHED in pHS-SM was found to be more directional. The presence of selected ten paracrine factors known for their proliferation and migration potential was detected in all six individual human sera, used to produce pHS, none of which were detected in FBS. Ingenuity Pathway Analysis showed the possible involvement of the 'ephrin receptor signalling pathway' to regulate the proliferation and migration of SHED in pHS-SM. In conclusion, pHS-SM showed significantly higher proliferation rate and could maintain significantly lower number of senescent cells and support directional migration of cells.

Characterization of Human AB Serum for Mesenchymal Stromal Cell Expansion

BACKGROUND

So far, using human blood-derived components appears to be the most efficient and safest approach available for mesenchymal stromal cell (MSC) expansion. In this paper, we report on the characterization of human AB serum (AB HS) produced by using different plasma sources, and its use as an alternative supplement to MSC expansion.

METHODS

Two plasma sources were used for AB HS production: plasma removed from whole blood after 24 h of collection (PC > 24 h) and plasma, cryoprecipitate reduced (PCryoR). The biochemical profile and quality of the produced AB HS batches were analyzed and their ability to support MSC cell growth after different storage times (0, 3, 6, 9 and 12 months) was evaluated.

RESULTS

The two plasma sources used showed similar characteristics regarding biochemical constituents and quality parameters and were effective in promoting MSC growth. MSCs cultured in medium supplemented with 10% AB HS presented similar doubling times and cumulative population doublings when compared to the 10% fetal bovine serum(FBS)-supplemented culture while maintaining immunophenotype, functional features, and cytogenetic profile.

CONCLUSION

Overall, the results indicate that AB HS is an efficient FBS substitute and can be used for at least 12 months after production without impairing cell proliferation and quality.

An Evaluation of the Stemness, Paracrine, and Tumorigenic Characteristics of Highly Expanded, Minimally Passaged Adipose-Derived Stem Cells

The use of adipose-derived stem cells (ADSC) in regenerative medicine is rising due to their plasticity, capacity of differentiation and paracrine and trophic effects. Despite the large number of cells obtained from adipose tissue, it is usually not enough for therapeutic purposes for many diseases or cosmetic procedures. Thus, there is the need for culturing and expanding cells in-vitro for several weeks remain. Our aim is to investigate if long- term proliferation with minimal passaging will affect the stemness, paracrine secretions and carcinogenesis markers of ADSC. The immunophenotypic properties and aldehyde dehydrogenase (ALDH) activity of the initial stromal vascular fraction (SVF) and serially passaged ADSC were observed by flow cytometry. In parallel, the telomerase activity and the relative expression of oncogenes and tumor suppressor genes were assessed by q-PCR. We also assessed the cytokine secretion profile of passaged ADSC by an ELISA. The expanded ADSC retain their morphological and phenotypical characteristics. These cells maintained in culture for up to 12 weeks until P4, possessed stable telomerase and ALDH activity, without having a TP53 mutation. Furthermore, the relative expression levels of TP53, RB, and MDM2 were not affected while the relative expression of c-Myc decreased significantly. Finally, the levels of the secretions of PGE₂, STC1, and TIMP2 were not affected but the levels of IL-6, VEGF, and TIMP 1 significantly decreased at P2. Our results suggest that the expansion of passaged ADSC does not affect the differentiation capacity of stem cells and does not confer a cancerous state or capacity in vitro to the cells.

Scalable microcarrier-based manufacturing of mesenchymal stem/stromal cells

Due to their unique features, mesenchymal stem/stromal cells (MSC) have been exploited in clinical settings as therapeutic candidates for the treatment of a variety of diseases. However, the success in obtaining clinically-relevant MSC numbers for cell-based therapies is dependent on efficient isolation and ex vivo expansion protocols, able to comply with good manufacturing practices (GMP). In this context, the 2-dimensional static culture systems typically used for the expansion of these cells present several limitations that may lead to reduced cell numbers and compromise cell functions. Furthermore, many studies in the literature report the expansion of MSC using fetal bovine serum (FBS)-supplemented medium, which has been critically rated by regulatory agencies. Alternative platforms for the scalable manufacturing of MSC have been developed, namely using microcarriers in bioreactors, with also a considerable number of studies now reporting the production of MSC using xenogeneic/serum-free medium formulations. In this review we provide a comprehensive overview on the scalable manufacturing of human mesenchymal stem/stromal cells, depicting the various steps involved in the process from cell isolation to ex vivo expansion, using different cell tissue sources and culture medium formulations and exploiting bioprocess engineering tools namely microcarrier technology and bioreactors.

Restoration of Mitochondrial NAD+ Levels Delays Stem Cell Senescence and Facilitates Reprogramming of Aged Somatic Cells

The fundamental tenet that aging is irreversible has been challenged by the development of reprogramming technology that can restore molecular and cellular age by reversing the progression of aging. The use of cells from aged individuals as sources for reprogramming or transplantation creates a major barrier in stem cell therapy with respect to cell quality and quantity. Here, we investigated the molecular features underlying senescence and rejuvenation during aged cell reprogramming and identified novel factors that can overcome age-associated barriers. Enzymes, such as nicotinamide nucleotide transhydrogenase (NNT) and nicotinamide mononucleotide adenylyltransferase 3 (NMNAT3), that control mitochondrial NAD⁺ levels appear to be susceptible to aging. In aged cells, mitochondrial NAD⁺ levels decrease, accompanied by reduced SIRT3 activity; these changes severely impede cell fate transition. However, in cells collected from aged p16 knockout mice, which exhibit delayed cellular senescence, no changes in NNT or NMNAT3 expression were found. Importantly, restoring mitochondrial NAD⁺ levels by overexpressing NNT and NMNAT3 enhanced reprogramming efficiency of aged somatic cells and extended the lifespan of human mesenchymal stem cells by delaying replicative senescence. These results demonstrate that maintenance of mitochondrial NAD⁺ levels is critical for reversing the mechanisms of aging and ensuring that cells collected from aged individuals are of high quality. Stem Cells 2016;34:2840-2851.