Gene and protein expression analysis of mesenchymal stem cells derived from rat adipose tissue and bone marrow

Secretome as a Tool to Treat Neurological Conditions: Are We Ready?

Due to their characteristics, mesenchymal stem cells (MSCs) are considered a potential therapy for brain tissue injury or degeneration. Nevertheless, despite the promising results observed, there has been a growing interest in the use of cell-free therapies in regenerative medicine, such as the use of stem cell secretome. This review provides an in-depth compilation of data regarding the secretome composition, protocols used for its preparation, as well as existing information on the impact of secretome administration on various brain conditions, pointing out gaps and highlighting relevant findings. Moreover, due to the ability of MSCs to respond differently depending on their microenvironment, preconditioning of MSCs has been used to modulate their composition and, consequently, their therapeutic potential. The different strategies used to modulate the MSC secretome were also reviewed. Although secretome administration was effective in improving functional impairments, regeneration, neuroprotection, and reducing inflammation in brain tissue, a high variability in secretome preparation and administration was identified, compromising the transposition of preclinical data to clinical studies. Indeed, there are no reports of the use of secretome in clinical trials. Despite the existing limitations and lack of clinical data, secretome administration is a potential tool for the treatment of various diseases that impact the CNS.

Potential of mesenchymal stem cell-derived conditioned medium/secretome as a therapeutic option for ocular diseases

Research has shown that the therapeutic effect of mesenchymal stem cells (MSCs) is partially due to its secreted factors as opposed to the implantation of the cells into the treated tissue or tissue replacement. MSC secretome, especially in the form of conditioned medium (MSC-CM) is now being explored as an alternative to MSCs transplantation. Despite the observed benefits of MSC-CM, only a few clinical trials have evaluated it and other secretome components in the treatment of eye diseases. This review provides insight into the potential therapeutic use of MSC-CM in eye conditions, such as corneal diseases, dry eye, glaucoma, retinal diseases and uveitis. We discuss the current evidence, some limitations, and the progress that remains to be achieved before clinical translation becomes possible.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Bone marrow-derived mesenchymal stem cell-conditioned medium ameliorates diabetic foot ulcers in rats

OBJECTIVES

This study aimed to explore the effects of bone marrow-derived Mesenchymal Stem Cell-Conditioned Medium (MSC-CM) treating diabetic foot ulcers in rats.

METHODS

Models of T2DM rats were induced by a high-fat diet and intraperitoneal injection of STZ in SD rats. Models of Diabetic Foot Ulcers (DFUs) were made by operation on hind limbs in diabetic rats. Rats were divided into four groups (n = 6 for each group), i.e., Normal Control group (NC), Diabetes Control group (DM-C), MSC-CM group and Mesenchymal Stem Cells group (MSCs). MSC-CM group was treated with an injection of conditioned medium derived from preconditioned rats' bone marrow MSCs around ulcers. MSCs group were treated with an injection of rats' bone marrow MSCs. The other two groups were treated with an injection of PBS. After the treatment, wound closure, re-epithelialization (thickness of the stratum granulosums of the skin, by H&E staining), cell proliferation (Ki67, by IHC), angiogenesis (CD31, by IFC), autophagy (LC3B, by IFC and WB; autolysosome, by EM) and pyroptosis (IL-1β, NLRP3, Caspase-1, GSDMD and GSDMD-N, by WB) in ulcers were evaluated.

RESULTS

After the treatment wound area rate, IL-1β by ELISA, and IL-1β, Caspase-1, GSDMD and GSDMD-N by WB of MSC-CM group were less than those of DM group. The thickness of the stratum granulosums of the skin, proliferation index of Ki67, mean optic density of CD31 and LC3B by IFC, and LC3B by WB of MSC-CM group were more than those of DM group. The present analysis demonstrated that the injection of MSC-CM into rats with DFUs enhanced the wound-healing process by accelerating wound closure, promoting cell proliferation and angiogenesis, enhancing cell autophagy, and reducing cell pyroptosis in ulcers.

CONCLUSIONS

Studies conducted indicate that MSC-CM administration could be a novel cell-free therapeutic approach to treat DFUs accelerating the wound healing process and avoiding the risk of living cells therapy.

Mesenchymal (Stem) Stromal Cells Based as New Therapeutic Alternative in Inflammatory Bowel Disease: Basic Mechanisms, Experimental and Clinical Evidence, and Challenges

Inflammatory bowel diseases (IBD) are an example of chronic diseases affecting 40% of the population, which involved tissue damage and an inflammatory process not satisfactorily controlled with current therapies. Data suggest that mesenchymal stem cells (MSC) may be a therapeutic option for these processes, and especially for IBD, due to their multifactorial approaches such as anti-inflammatory, anti-oxidative stress, anti-apoptotic, anti-fibrotic, regenerative, angiogenic, anti-tumor, or anti-microbial. However, MSC therapy is associated with important limitations as safety issues, handling difficulties for therapeutic purposes, and high economic cost. MSC-derived secretome products (conditioned medium or extracellular vesicles) are therefore a therapeutic option in IBD as they exhibit similar effects to their parent cells and avoid the issues of cell therapy. In this review, we proposed further studies to choose the ideal tissue source of MSC to treat IBD, the implementation of new standardized production strategies, quality controls and the integration of other technologies, such as hydrogels, which may improve the therapeutic effects of derived-MSC secretome products in IBD.

Paracrine Factors Released by Stem Cells of Mesenchymal Origin and their Effects in Cardiovascular Disease: A Systematic Review of Pre-clinical Studies

Mesenchymal stem cell (MSC) therapy has gained significant traction in the context of cardiovascular repair, and have been proposed to exert their regenerative effects via the secretion of paracrine factors. In this systematic review, we examined the literature and consolidated available evidence for the “paracrine hypothesis”. Two Ovid SP databases were searched using a strategy encompassing paracrine mediated MSC therapy in the context of ischemic heart disease. This yielded 86 articles which met the selection criteria for inclusion in this study. We found that the MSCs utilized in these articles were primarily derived from bone marrow, cardiac tissue, and adipose tissue. We identified 234 individual protective factors across these studies, including VEGF, HGF, and FGF2; which are proposed to exert their effects in a paracrine manner. The data collated in this systematic review identifies secreted paracrine factors that could decrease apoptosis, and increase angiogenesis, cell proliferation, and cell viability. These included studies have also demonstrated that the administration of MSCs and indirectly, their secreted factors can reduce infarct size, and improve left ventricular ejection fraction, contractility, compliance, and vessel density. Furthering our understanding of the way these factors mediate repair could lead to the identification of therapeutic targets for cardiac regeneration.

Angiogenic efficacy of ASC spheroids filtrated on porous nanosheets for the treatment of a diabetic skin ulcer

Stem cell transplantation is expected to be an effective treatment for intractable skin ulcers by promoting angiogenesis; however, it is challenging to quickly realize a sufficient bloodstream for the ulcers. For this treatment, sheet-like materials with monolayer cells such as cell sheets have been investigated. However, they have a limitation of cell number that can be transplanted at one time due to the two-dimensional, monolayer cell structure, and sufficient secretion of growth factors cannot be expected. In this regard, cellular aggregates, such as spheroids, can reproduce three-dimensional cell-cell interactions that cause biological functions of living tissues more representative than monolayer cells, which is important to achieving efficient secretion of growth factors. In this study, we focused on free-standing porous polymer ultrathin films ("porous nanosheets") comprising poly(d,l-lactic acid) (PDLLA) and succeeded in developing a spheroid-covered nanosheet, on which more than 1000 spheroids from adipose-tissue derived stem cells (ASCs) were loaded. The porous structure with an average pore diameter of 4 μm allowed for facile filtration and carrying spheroids on the nanosheet, as well as sufficient oxygen and nutrients inflow to the cells. The spheroid-covered nanosheet achieved homogeneous transference of spheroids to a whole skin defect in diabetic model mice. Given the continuous release of vascular endothelial growth factor (VEGF) from the spheroids, the transplanted spheroids promoted healing with more accelerated angiogenesis than a nanosheet with a monolayer of cells. The spheroid-covered nanosheet may be a new regenerative material for promoting intractable skin ulcer healing.

Secretome Analysis of Rabbit and Human Mesenchymal Stem and Endothelial Progenitor Cells: A Comparative Study

Human adipose tissue-derived mesenchymal stem cells (AT-MSCs) have been studied several years for their immunomodulatory effect through the paracrine mechanism and cytokine secretion. In combination with endothelial progenitor cells (EPCs), MSCs have great therapeutical potential for the repair of endothelium and wound healing. However, little is known about the cytokine profile of rabbit AT-MSCs or even EPCs. The aim of this study was to analyze the secretomes of these rabbit stem/progenitor cells. A large-scale human cytokine array (up to 80 cytokines) was used to identify and compare cytokines secreted into conditioned media of human and rabbit AT-MSCs as well as HUVECs and rabbit EPCs. Few cytokines were highly expressed by human AT-MSCs (TIMP-2, TIMP-1), HUVECs (MCP-1, TIMP-2, GRO, Angiogenin, IL-8, TIMP-1), or by rabbit EPCs (TIMP-2). Several cytokines have moderate expression by human (MCP-1, GRO, Angiogenin, TGF-β 2, IL-8, LIF, IL-6, Osteopontin, Osteoprotegerin) and rabbit AT-MSCs (TIMP-2, TGF-β 2, LIF, Osteopontin, IL-8, IL-5, IL-3) or by HUVECs (IL-6, MIF, TGF-β 2, GCP-2, IGFBP-2, Osteoprotegerin, EGF, LIF, PDGF-BB, MCP-3, Osteopontin, Leptin, IL-5, ENA-78, TNF-β) and rabbit EPCs (TGF-β 2, Osteopontin, GRO, LIF, IL-8, IL-5, IL-3). In conclusion, the proposed method seems to be useful for the secretome analysis of rabbit stem/progenitor cells.

Angiogenic Effects and Crosstalk of Adipose-Derived Mesenchymal Stem/Stromal Cells and Their Extracellular Vesicles with Endothelial Cells

Adipose-derived mesenchymal stem/stromal cells (ASCs) are an adult stem cell population able to self-renew and differentiate into numerous cell lineages. ASCs provide a promising future for therapeutic angiogenesis due to their ability to promote blood vessel formation. Specifically, their ability to differentiate into endothelial cells (ECs) and pericyte-like cells and to secrete angiogenesis-promoting growth factors and extracellular vesicles (EVs) makes them an ideal option in cell therapy and in regenerative medicine in conditions including tissue ischemia. In recent angiogenesis research, ASCs have often been co-cultured with an endothelial cell (EC) type in order to form mature vessel-like networks in specific culture conditions. In this review, we introduce co-culture systems and co-transplantation studies between ASCs and ECs. In co-cultures, the cells communicate via direct cell-cell contact or via paracrine signaling. Most often, ASCs are found in the perivascular niche lining the vessels, where they stabilize the vascular structures and express common pericyte surface proteins. In co-cultures, ASCs modulate endothelial cells and induce angiogenesis by promoting tube formation, partly via secretion of EVs. In vivo co-transplantation of ASCs and ECs showed improved formation of functional vessels over a single cell type transplantation. Adipose tissue as a cell source for both mesenchymal stem cells and ECs for co-transplantation serves as a prominent option for therapeutic angiogenesis and blood perfusion in vivo.

Intestinal mesenchymal cells regulate immune responses and promote epithelial regeneration in vitro and in dextran sulfate sodium-induced experimental colitis in mice

AIM

Disruption of the intestinal mucosal tolerance, that is, the immunological unresponsiveness to innocuous food antigens and the commensal microbiota, in the colon is associated with several chronic diseases including inflammatory bowel disease (IBD). Understanding the mechanisms responsible for intestinal mucosal tolerance has potential translational value for its therapy and management. Human intestinal mesenchymal cells (iMCs) play important roles in colonic mucosal tolerance, but further studies on their tissue regenerative and immunomodulatory capacities are necessary in order to fully understand their function in health and disease.

METHODS

In this study, we have isolated and analysed the capacity of human iMCs to promote wound healing and modulate immune responses in vitro and in vivo, using the dextran sulfate sodium (DSS)-induced colitis model.

RESULTS

Cultured iMCs were CD45^- CD73⁺ CD90⁺ CD105⁺ and accelerated the wound closure in a normal colon mucosa (NCM) 356 human epithelial cell wound healing assay. Furthermore, iMCs blocked the LPS-mediated induction of TNF-α in THP-1 macrophages and inhibited the proliferation of peripheral blood mononuclear cells, partly through the induction of indoleamine-2,3-dioxygenase. In DSS colitic mice, iMCs administration reduced the disease activity index and ameliorated intestinal tissue damage and permeability. Furthermore, iMCs reduced intestinal inflammation, evidenced by a decreased mRNA expression of pro-inflammatory cytokines, reduced IL-1β secretion by intestinal explants and inhibited colonic iNOS protein expression.

CONCLUSIONS

Our data show that human iMCs isolated from the noninflamed intestine possess tissue-regenerative and immunomodulatory capacities that could potentially be harnessed/restored in order to reduce IBD severity.

Cardiac Differentiation of Mesenchymal Stem Cells: Impact of Biological and Chemical Inducers

Cardiovascular disorders (CVDs) are the leading cause of global death, widely occurs due to irreparable loss of the functional cardiomyocytes. Stem cell-based therapeutic approaches, particularly the use of Mesenchymal Stem Cells (MSCs) is an emerging strategy to regenerate myocardium and thereby improving the cardiac function after myocardial infarction (MI). Most of the current approaches often employ the use of various biological and chemical factors as cues to trigger and modulate the differentiation of MSCs into the cardiac lineage. However, the recent advanced methods of using specific epigenetic modifiers and exosomes to manipulate the epigenome and molecular pathways of MSCs to modify the cardiac gene expression yield better profiled cardiomyocyte like cells in vitro. Hitherto, the role of cardiac specific inducers triggering cardiac differentiation at the cellular and molecular level is not well understood. Therefore, the current review highlights the impact and recent trends in employing biological and chemical inducers on cardiac differentiation of MSCs. Thereby, deciphering the interactions between the cellular microenvironment and the cardiac inducers will help us to understand cardiomyogenesis of MSCs. Additionally, the review also provides an insight on skeptical roles of the cell free biological factors and extracellular scaffold assisted mode for manipulation of native and transplanted stem cells towards translational cardiac research.

Differential Therapeutic Effect of Extracellular Vesicles Derived by Bone Marrow and Adipose Mesenchymal Stem Cells on Wound Healing of Diabetic Ulcers and Correlation to Their Cargoes

Extracellular vesicles (EVs) derived from mesenchymal stem cells isolated from both bone marrow (BMSCs) and adipose tissue (ADSCs) show potential therapeutic effects. These vesicles often show a similar beneficial effect on tissue regeneration, but in some contexts, they exert different biological properties. To date, a comparison of their molecular cargo that could explain the different biological effect is not available. Here, we demonstrated that ADSC-EVs, and not BMSC-EVs, promote wound healing on a murine model of diabetic wounds. Besides a general similarity, the bioinformatic analysis of their protein and miRNA cargo highlighted important differences between these two types of EVs. Molecules present exclusively in ADSC-EVs were highly correlated to angiogenesis, whereas those expressed in BMSC-EVs were preferentially involved in cellular proliferation. Finally, in vitro analysis confirmed that both ADSC and BMSC-EVs exploited beneficial effect on cells involved in skin wound healing such as fibroblasts, keratinocytes and endothelial cells, but through different cellular processes. Consistent with the bioinformatic analyses, BMSC-EVs were shown to mainly promote proliferation, whereas ADSC-EVs demonstrated a major effect on angiogenesis. Taken together, these results provide deeper comparative information on the cargo of ADSC-EVs and BMSC-EVs and the impact on regenerative processes essential for diabetic wound healing.

Ultra-thin, transparent, porous substrates as 3D culture scaffolds for engineering ASC spheroids for high-magnification imaging

Three-dimensional (3D) culture is expected to reproduce biological tissues more representatively than monolayer culture, which is important for in vitro research such as drug screening. Recently, various cell culture substrates for spheroid engineering have been developed based on the prevention of cell adhesion. However, despite the expanded usability these substrates provide, they remain limited in terms of optical microscopy imaging of spheroids with high magnification lenses. This is because almost all substrates generated by nanoimprinting hamper the light passing through them owing to their low optical transparency caused by the thickness and surface structure. In this study, we achieved the preparation of spheroids from adipose-tissue derived stem cells (ASCs) on free-standing porous polymeric ultrathin films ("porous nanosheets") consisting of poly(d,l-lactic acid) (PDLLA) with thickness of 120 nm and average pore diameter of 4 μm. ASCs migrated on the porous nanosheet, leading to the spontaneous organization of spheroids anchored via a cell monolayer. The porous nanosheet also provided more than twice the optical transparency in confocal and holographic microscopy observation compared to conventional nanoimprinted substrates for 3D cell culture (NanoCulture Dish). The internal structure of the organized spheroids could be clearly observed with 40× magnification. In addition, the engineered spheroids showed bioactivities indicated by mRNA expression of fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF). Thus, porous nanosheets offer a unique cell culture substrate, not only for engineering 3D cellular organization from stem cells, but also for imaging detailed structure using light microscopy.

Effects of the histone acetylase inhibitor C646 on growth and differentiation of adipose-derived stem cells

As an important histone acetylase, the transcriptional coactivator P300/CBP affects target gene expression and plays a role in the maintenance of stem cell characteristics and differentiation potential. In this study, we explored the action of a highly effective selective histone acetylase inhibitor, C646, on goat adipose-derived stem cells (gADSCs), and investigated the impact of histone acetylation on the growth characteristics and the differentiation potential of ADSCs. We found that C646 blocked the cell proliferation, arrested the cell cycle, and triggered apoptosis. Notably, immunocytochemistry and western blot analyses showed that the acetylation level of histone H3K9 was increased. Moreover, although real-time quantitative PCR and western blot confirmed that P300 expression was inhibited under these conditions, the expression level of two other histone acetylases, TIP60 and PCAF, was significantly increased. Furthermore, C646 clearly promoted the differentiation of gADSCs into adipocytes and had an impact on their differentiation into neuronal cells. This study provides new insights into the epigenetic regulation of stem cell differentiation and may represent an experimental basis for the comprehension of stem cell characteristics and function. Furthermore, it is of great relevance for the application of adult stem cells to somatic cell cloning, which may improve the efficiency of large livestock cloning and foster the production of transgenic animals.

Mesenchymal stromal cells for systemic sclerosis treatment

Systemic sclerosis (SSc) is a rare chronic autoimmune disease characterized by vasculopathy, dysregulation of innate and adaptive immune responses, and progressive fibrosis. SSc remains an orphan disease, with high morbity and mortality in SSc patients. The mesenchymal stromal cells (MSC) demonstrate in vitro and in vivo pro-angiogenic, immuno-suppressive, and anti-fibrotic properties and appear as a promising stem cell therapy type, that may target the key pathological features of SSc disease. This review aims to summarize acquired knowledge in the field of :1) MSC definition and in vitro and in vivo functional properties, which vary according to the donor type (allogeneic or autologous), the tissue sources (bone marrow, adipose tissue or umbilical cord) or inflammatory micro-environment in the recipient; 2) preclinical studies in various SSc animal models , which showed reduction in skin and lung fibrosis after MSC infusion; 3) first clinical trials in human, with safety and early efficacy results reported in SSc patients or currently tested in several ongoing clinical trials.

Comparative Proteomic Analysis of the Mesenchymal Stem Cells Secretome from Adipose, Bone Marrow, Placenta and Wharton's Jelly

Mesenchymal stem cells (MSCs) have the potential to be a viable therapy against various diseases due to their paracrine effects, such as secretion of immunomodulatory, trophic and protective factors. These cells are known to be distributed within various organs and tissues. Although they possess the same characteristics, MSCs from different sources are believed to have different secretion potentials and patterns, which may influence their therapeutic effects in disease environments. We characterized the protein secretome of adipose (AD), bone marrow (BM), placenta (PL), and Wharton’s jelly (WJ)-derived human MSCs by using conditioned media and analyzing the secretome by mass spectrometry and follow-up bioinformatics. Each MSC secretome profile had distinct characteristics depending on the source. However, the functional analyses of the secretome from different sources showed that they share similar characteristics, such as cell migration and negative regulation of programmed cell death, even though differences in the composition of the secretome exist. This study shows that the secretome of fetal-derived MSCs, such as PL and WJ, had a more diverse composition than that of AD and BM-derived MSCs, and it was assumed that their therapeutic potential was greater because of these properties.

Paracrine effect of human adipose-derived stem cells on lymphatic endothelial cells

Aim: The proposal of this study was to evaluate, in vitro, the potential paracrine effect of human adipose-derived stem cells (hASCs) to promote lymphangiogenesis in lymphatic endothelial cells isolated from rat diaphragmatic lymphatic vessels. Materials & methods: ELISA on VEGFA, VEGFC and IL6 in hASC-conditioned medium; LYVE1 immunostaining; and gene expression of PROX1, VEGFR3, VEGFC, VEGFA and IL6 were the methods used. Results: In 2D culture, hASC-conditioned medium was able to promote lymphatic endothelial cell survival, maintenance of endothelial cobblestone morphology and induction to form a vessel-like structure. Conclusion: The authors' results represent in vitro evidence of the paracrine effect of hASCs on lymphatic endothelial cells, suggesting the possible role of hASC-conditioned medium in developing new therapeutic approaches for lymphatic system-related dysfunction such as secondary lymphedema.

Prospect of stem cells conditioned medium (secretome) in ligament and tendon healing: A systematic review

BACKGROUND

Tendon or ligament tears can decrease patients' quality of life. Many therapeutic interventions are available to treat such injuries. Mesenchymal stem cells (MSCs) have been shown to be effective in treating tendon or ligament tears; however, the use of stem cell-conditioned medium (CM) requires further investigation. This review focused on the use of stem cell CM as treatment for tendon or ligament tears.

METHODS

A systematic literature search was performed on PubMed (MEDLINE), OVID, EMBASE, the Cochrane Library, Scopus, Web of Science, and Science Direct with the terms conditioned media or conditioned medium or secretome or microvesicle or extracellular vesicle or exosome, and tendon or ligament as the search keywords. A total of 852 articles were reviewed. Five articles were identified as relevant for this systematic review.

RESULTS

Meta-analysis could not be performed because of the high heterogeneity of the reviewed studies; however, the results of this study support a positive effect of conditioned media in tendon and ligament treatment.

CONCLUSION

This review provides evidence of improvement in the tendon and ligament healing process with stem cell CM therapy in preclinical studies.

A comparative study on normal and obese mice indicates that the secretome of mesenchymal stromal cells is influenced by tissue environment and physiopathological conditions

Background

The term mesenchymal stromal cells (MSCs) designates an assorted cell population comprised of stem cells, progenitor cells, fibroblasts, and stromal cells. MSCs contribute to the homeostatic maintenance of many organs through paracrine and long-distance signaling.

Tissue environment, in both physiological and pathological conditions, may affect the intercellular communication of MSCs.

Methods

We performed a secretome analysis of MSCs isolated from subcutaneous adipose tissue (sWAT) and visceral adipose tissue (vWAT), and from bone marrow (BM), of normal and obese mice.

Results

The MSCs isolated from tissues of healthy mice share a common core of released factors: components of cytoskeletal and extracellular structures; regulators of basic cellular functions, such as protein synthesis and degradation; modulators of endoplasmic reticulum stress; and counteracting oxidative stress. It can be hypothesized that MSC secretome beneficially affects target cells by the horizontal transfer of many released factors. Each type of MSC may exert specific signaling functions, which could be determined by looking at the many factors that are exclusively released from every MSC type.

The vWAT-MSCs release factors that play a role in detoxification activity in response to toxic substances and drugs. The sWAT-MSC secretome contains proteins involved in in chondrogenesis, osteogenesis, and angiogenesis. Analysis of BM-MSC secretome revealed that these cells exert a signaling function by remodeling extracellular matrix structures, such as those containing glycosaminoglycans. Obesity status profoundly modified the secretome content of MSCs, impairing the above-described activity and promoting the release of inflammatory factors.

Conclusion

We demonstrated that the content of MSC secretomes depends on tissue microenvironment and that pathological condition may profoundly alter its composition.

In vitro Evaluation of ASCs and HUVECs Co-cultures in 3D Biodegradable Hydrogels on Neurite Outgrowth and Vascular Organization

Vascular disruption following spinal cord injury (SCI) decisively contributes to the poor functional recovery prognosis facing patients with the condition. Using a previously developed gellan gum hydrogel to which the adhesion motif GRGDS was grafted (GG-GRGDS), this work aimed to understand the ability of adipose-derived stem cells (ASCs) to impact vascular organization of human umbilical vein endothelial cells (HUVECs), and how this in turn affects neurite outgrowth of dorsal root ganglia (DRG) explants. Our data shows that culturing these cells together lead to a synergistic effect as showed by increased stimulation of neuritogenesis on DRG. Importantly, HUVECs were only able to assemble into vascular-like structures when cultured in the presence of ASCs, which shows the capacity of these cells in reorganizing the vascular milieu. Analysis of selected neuroregulatory molecules showed that the co-culture upregulated the secretion of several neurotrophic factors. On the other hand, ASCs, and ASCs + HUVECs presented a similar profile regarding the presence of angiotrophic molecules herein analyzed. Finally, the implantation of GG-GRGDS hydrogels encapsulating ASCs in the chick chorioallantoic membrane (CAM) lead to increases in vascular recruitment toward the hydrogels in comparison to GG-GRGDS alone. This indicates that the combination of ASCs with GG-GRGDS hydrogels could promote re-vascularization in trauma-related injuries in the central nervous system and thus control disease progression and induce functional recovery.

Adipose tissue and the vascularization of biomaterials: Stem cells, microvascular fragments and nanofat-a review

Tissue defects in the human body after trauma and injury require precise reconstruction to regain function. Hence, there is a great demand for clinically translatable approaches with materials that are both biocompatible and biodegradable. They should also be able to adequately integrate within the tissue through sufficient vascularization. Adipose tissue is abundant and easily accessible. It is a valuable tissue source in regenerative medicine and tissue engineering, especially with regard to its angiogenic potential. Derivatives of adipose tissue, such as microfat, nanofat, microvascular fragments, stromal vascular fraction and stem cells, are commonly used in research, but also clinically to enhance the vascularization of implants and grafts at defect sites. In plastic surgery, adipose tissue is harvested via liposuction and can be manipulated in three ways (macro-, micro- and nanofat) in the operating room, depending on its ultimate use. Whereas macro- and microfat are used as a filling material for soft tissue injuries, nanofat is an injectable viscous extract that primarily induces tissue remodeling because it is rich in growth factors and stem cells. In contrast to microfat that adds volume to a defect site, nanofat has the potential to be easily combined with scaffold materials due to its liquid and homogenous consistency and is particularly attractive for blood vessel formation. The same is true for microvascular fragments that are easily isolated from adipose tissue through collagenase digestion. In preclinical animal models, it has been convincingly shown that these vascular fragments inosculate with host vessels and subsequently accelerate scaffold perfusion and host tissue integration. Adipose tissue is also an ideal source of stem cells. It yields larger quantities of cells than any other source and is easier to access for both the patient and doctor compared with other sources such as bone marrow. They are often used for tissue regeneration in combination with biomaterials. Adipose-derived stem cells can be applied unmodified or as single cell suspensions. However, certain pretreatments, such as cultivation under hypoxic conditions or three-dimensional spheroids production, may provide substantial benefit with regard to subsequent vascularization in vivo due to induced growth factor production. In this narrative review, derivatives of adipose tissue and the vascularization of biomaterials are addressed in a comprehensive approach, including several sizes of derivatives, such as whole fat flaps for soft tissue engineering, nanofat or stem cells, their secretome and exosomes. Taken together, it can be concluded that adipose tissue and its fractions down to the molecular level promote, enhance and support vascularization of biomaterials. Therefore, there is a high potential of the individual fat component to be used in regenerative medicine.

Effectiveness of Adhering Adipose-Derived Stem Cells to Defective Cartilage in Promoting Cartilage Regeneration in a Rabbit Model

PURPOSE

To evaluate the therapeutic effect of using a local adherent technique to transplant adipose-derived stem cells (ADSCs) for cartilage regeneration in a rabbit model for patients with traumatic damage or osteochondritis dissecans.

METHODS

Cartilage defects were created in the trochlear groove of 60 adult white rabbit knees. The rabbits were either left untreated (control group), treated with intra-articularly injected ADSCs (injected group), or treated by adhering ADSCs (adherent group). The 3 groups were compared at 4, 12, and 24 weeks postoperatively using the International Cartilage Repair Society macroscopic scoring system and a modified Wakitani histologic grading system to quantitatively evaluate the regenerated cartilage. The degree of defect repair, integration to the border zone, macroscopic appearance, cell morphology, matrix staining, surface regularity, cartilage thickness, and integration of the donor with the host were evaluated.

RESULTS

The mean International Cartilage Repair Society scores in the control, injected, and adherent groups were 6.4 ± 2.9, 7.6 ± 0.8, and 7.6 ± 1.4, respectively, at 4 weeks; 6.2 ± 2.4, 8.2 ± 1.5, and 9.6 ± 1.0, respectively, at 8 weeks; and 7.6 ± 1.0, 8.4 ± 1.4, and 10.2 ± 1.7, respectively, at 24 weeks. Although the scores were higher in the adherent group, no significant difference was noted. The mean modified Wakitani scores in the control, injected, and adherent groups were 3.8 ± 2.0, 5.1 ± 1.8, and 7.8 ± 1.3, respectively, at 4 weeks (P = .041); 5.1 ± 1.0, 5.4 ± 2.7, and 9.6 ± 1.4, respectively, at 12 weeks (P = .016); and 5.4 ± 1.0, 5.9 ± 1.5, and 9.8 ± 1.8, respectively, at 24 weeks (P = .007).

CONCLUSIONS

The histologic modified Wakitani scores showed that adhering ADSCs to osteochondral cartilage defects was more effective than intra-articular injection for promoting cartilage regeneration.

CLINICAL RELEVANCE

Local adhesion of ADSCs can promote cartilage regeneration and may be a treatment option for cartilage repair.

Epigallocatechin-3-gallate enhances the osteoblastogenic differentiation of human adipose-derived stem cells

Purpose

The aim of this study is to investigate the effects of epigallocatechin-3-gallate (EGCG), a major polyphenol extracted from green tea, on the osteoblastogenic differentiation of human adipose-derived stem cells (hASCs).

Patients and methods

hASCs were acquired from human adipose tissue. With informed consent, subcutaneous adipose tissue samples were harvested from periorbital fat pad resections from ten healthy female adults who underwent double eyelid surgery. hASCs were cultured in osteogenic medium with or without EGCG (1 μM, 5 μM, or 10 μM) for 14 days. We evaluated the effects of EGCG by quantifying cell growth, ALP activity (an early osteoblastogenic differentiation marker), BSP, OCN (a late osteoblastogenic differentiation marker), and extracellular matrix mineralization. We also performed Western blots to measure osteoblastogenesis-related proteins such as Runx2 and adipoblastogenesis-related transcription factors, such as STAT3, C/EBP-α, and PPAR-γ.

Results

EGCG at 5 μM resulted in significantly higher cell proliferation and ALP activity than did the control on days 3, 7, and 14. On day 7, 5 μM EGCG significantly enhanced BSP expression. On day 14, EGCG at all concentrations promoted OCN expression. In addition, EGCG at 5 μM resulted in the highest level of extracellular matrix mineralization. On day 3, the expression levels of Runx2 were significantly higher in the 5 μM EGCG group than in the other groups, whereas later, on days 7 and 14, Runx2 expression levels in the EGCG group were significantly lower than those of the control group. EGCG at all three concentrations was associated with significantly lower levels of phosphorylated STAT3, C/EBP-α, and PPAR-γ.

Conclusion

EGCG at 5 μM significantly enhanced the osteoblastogenic differentiation of hASCs.

Effect of strontium substituted ß-TCP associated to mesenchymal stem cells from bone marrow and adipose tissue on spinal fusion in healthy and ovariectomized rat

Despite alternatives to autogenous bone graft for spinal fusion have been investigated, it has been shown that osteoconductive materials alone do not give a rate of fusion comparable with autogenous bone. This study analyzed a strontium substituted ß-tricalcium phosphate (Sr-ßTCP) associated with syngeneic, unexpanded, and undifferentiated mesenchymal stem cells from bone marrow (BMSC) or adipose tissue (ADSC) as a new tissue engineering approach for spinal fusion procedures. A posterolateral fusion was performed in 15 ovariectomized (OVX) and 15 sham-operated (SHAM) Inbred rats. Both SHAM and OVX animals were divided into three groups: Sr-ßTCP, Sr-ßTCP + BMCSs, and Sr-ßTCP + ADSCs. Animals were euthanized 8 weeks after surgery and the spines evaluated by manual palpation, micro-CT, and histology. For both SHAM and OVX animals, the fusion tissue in the Sr-ßTCP + BMSCs group was more solid. This effect was significantly higher in OVX animals by comparing the Sr-ßTCP + BMCSs group with Sr-ßTCP + ADSCs. Radiographical score, based on micro-CT 2D image, highlighted that the Sr-ßTCP + BMCSs group presented a similar fusion to Sr-ßTCP and higher than Sr-ßTCP + ADSCs in both SHAM and OVX animals. Micro-CT 3D parameters did not show significant differences among groups. Histological score showed significantly higher fusion in Sr-ßTCP + BMSCs group than Sr-ßTCP and Sr-ßTCP + ADSCs, for both SHAM and OVX animals. In conclusion, our results suggest that addition of BMSCs to a Sr-ßTCP improve bone formation and fusion, both in osteoporotic and nonosteoporotic animal, whereas spinal fusion is not enhanced in rats treated with Sr-ßTCP + ADSCs. Thus, for conducting cells therapy in spinal surgery BMSCs still seems to be a better choice compared with ADSCs.

Adipose-derived stem cell sheets accelerate bone healing in rat femoral defects

In the present study, we investigated whether both adipose-derived stem cell (ADSC) and osteogenic-induced ADSC sheets could promote bone healing in a rat distal femoral metaphysis bone defect model. A through-hole defect of 1 mm diameter was drilled into each distal femur of 12 week old rats. Forty-five rats were randomly assigned to three groups: (1) control group; (2) ADSC sheet group; or (3) osteogenic-induced ADSC sheet group. We evaluated each group by analysis of computerized tomography scans every week after the surgery, histological analysis, and DiI labeling (a method of membrane staining for post implant cell tracing). Radiological and histological evaluations showed that a part of the hole persisted in the control group at four weeks after surgery, whereas the hole was restored almost completely by new bone formation in both sheet groups. The mean value of bone density (in Houndsfield units) for the bone defect area was significantly higher in both sheet groups than that in the control group (p = 0.05) at four weeks postoperative. A large number of osteocalcin positive osteoblasts were observed at the area of bone defect, especially in the osteogenic-induced ADCS sheet group. DiI labeling in the newly formed bone showed that each sheet had differentiated into bone tissue at four weeks after surgery. The ADSC and the osteogenic-induced ADSC sheets promoted significantly quicker bone healing in the bone defect. Moreover, the osteogenic-induced ADSC sheet may be more advantageous for bone healing than the ADSC sheet because of the higher number of osteocalcin positive osteoblasts via the transplantation.

In situ transplantation of adipose tissue-derived stem cells organized on porous polymer nanosheets for murine skin defects

Stem cell transplantation is expected to be an effective early-phase treatment for deep burn injuries and intractable ulcers. Localizing and proliferating stem cells on the lesion utilizing engineered scaffolds is important for this treatment. In this study, we demonstrated in situ transplantation of adipose-tissue derived stem cells (ASCs) organized on free-standing porous polymer ultrathin films (referred to as "porous nanosheets") to a skin defect model in diabetic mice. Porous nanosheets were prepared by a combination of micro-gravure coating with macrophase separation of poly(d,l-lactic acid) and polystyrene under a roll-to-roll process and solvent etching process with cyclohexane. The permeable structure of porous nanosheets (thickness of 150 nm, average pore diameter of 4 μm) allowed for proliferation of ASCs and also provided sufficient nutrient inflow into multilayered ASC constructs. Then, transplantation of a trilayered ASC-laden porous nanosheet achieved homogeneous transference of ASCs onto the skin lesion. Transplanted ASCs contributed to wound healing in a dorsal skin defect model in diabetic mice. Thus, cell transplantation using porous nanosheets will be a new method for promoting wound healing in diabetic and other kinds of refractory ulcers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1363-1371, 2019.

Exploiting the impact of the secretome of MSCs isolated from different tissue sources on neuronal differentiation and axonal growth

Cell transplantation using Mesenchymal stem cell (MSC) secretome have recently been presented as a possible free-based therapy for CNS related disorders. MSC secretome is rich in several bio-factors that act synergically towards the repair of damaged tissues, thus making it an ideal candidate for regenerative applications. Great effort is currently being made to map the molecules that compose the MSC secretome. Previous proteomic characterization of the secretome (in the form of conditioned media - CM) of MSCs derived from adipose tissue (ASC), bone-marrow (BMSC) and umbilical cord (HUCPVC) was performed by our group, where proteins relevant for neuroprotection, neurogenic, neurodifferentiation, axon guidance and growth functions were identified. Moreover, we have found significant differences among the expression of several molecules, which may indicate that their therapeutic outcome might be distinct. Having this in mind, in the present study, the neuroregulatory potential of ASC, BMSC and HUCPVC CM in promoting neurodifferentiation and axonal outgrowth was tested in vitro, using human telencephalon neuroprogenitor cells and dorsal root ganglion explants, respectively. The CM from the three MSC populations induced neuronal differentiation from human neural progenitor cells, as well as neurite outgrowth from dorsal root ganglion explants. Moreover, all the MSC populations promoted the same extent of neurodifferentiation, while ASC CM demonstrated higher potential in promoting axonal growth.

Revisiting the Advances in Isolation, Characterization and Secretome of Adipose-Derived Stromal/Stem Cells

Adipose-derived stromal/stem cells (ASCs) seems to be a promising regenerative therapeutic agent due to the minimally invasive approach of their harvest and multi-lineage differentiation potential. The harvested adipose tissues are further digested to extract stromal vascular fraction (SVF), which is cultured, and the anchorage-dependent cells are isolated in order to characterize their stemness, surface markers, and multi-differentiation potential. The differentiation potential of ASCs is directed through manipulating culture medium composition with an introduction of growth factors to obtain the desired cell type. ASCs have been widely studied for its regenerative therapeutic solution to neurologic, skin, wound, muscle, bone, and other disorders. These therapeutic outcomes of ASCs are achieved possibly via autocrine and paracrine effects of their secretome comprising of cytokines, extracellular proteins and RNAs. Therefore, secretome-derivatives might offer huge advantages over cells through their synthesis and storage for long-term use. When considering the therapeutic significance and future prospects of ASCs, this review summarizes the recent developments made in harvesting, isolation, and characterization. Furthermore, this article also provides a deeper insight into secretome of ASCs mediating regenerative efficacy.

Impact of Age on Human Adipose Stem Cells for Bone Tissue Engineering

Bone nonunion is a pathological condition in which all bone healing processes have stopped, resulting in abnormal mobility between 2 bone segments. The incidence of bone-related injuries will increase in an aging population, leading to such injuries reaching epidemic proportions. Tissue engineering and cell therapy using mesenchymal stem cells (MSCs) have raised the possibility of implanting living tissue for bone reconstruction. Bone marrow was first proposed as the source of stem cells for bone regeneration. However, as the quantity of MSCs in the bone marrow decreases, the capacity of osteogenic differentiation of bone marrow stem cells is also impaired by the donor's age in terms of reduced MSC replicative capacity; an increased number of apoptotic cells; formation of colonies positive for alkaline phosphatase; and decreases in the availability, growth potential, and temporal mobilization of MSCs for bone formation in case of fracture. Adipose-derived stem cells (ASCs) demonstrate several advantages over those from bone marrow, including a less invasive harvesting procedure, a higher number of stem cell progenitors from an equivalent amount of tissue harvested, increased proliferation and differentiation capacities, and better angiogenic and osteogenic properties in vivo. Subcutaneous native adipose tissue was not affected by the donor's age in terms of cellular senescence and yield of ASC isolation. In addition, a constant mRNA level of osteocalcin and alkaline phosphatase with a similar level of matrix mineralization of ASCs remained unaffected by donor age after osteogenic differentiation. The secretome of ASCs was also unaffected by age when aiming to promote angiogenesis by vascular endothelial growth factor (VEGF) release in hypoxic conditions. Therefore, the use of adipose cells for bone tissue engineering is not limited by the donor's age from the isolation of stem cells up to the manufacturing of a complex osteogenic graft.

Mesenchymal Stem Cell-Based Therapy for Cardiovascular Disease: Progress and Challenges

Administration of mesenchymal stem cells (MSCs) to diseased hearts improves cardiac function and reduces scar size. These effects occur via the stimulation of endogenous repair mechanisms, including regulation of immune responses, tissue perfusion, inhibition of fibrosis, and proliferation of resident cardiac cells, although rare events of transdifferentiation into cardiomyocytes and vascular components are also described in animal models. While these improvements demonstrate the potential of stem cell therapy, the goal of full cardiac recovery has yet to be realized in either preclinical or clinical studies. To reach this goal, novel cell-based therapeutic approaches are needed. Ongoing studies include cell combinations, incorporation of MSCs into biomaterials, or pre-conditioning or genetic manipulation of MSCs to boost their release of paracrine factors, such as exosomes, growth factors, microRNAs, etc. All of these approaches can augment therapeutic efficacy. Further study of the optimal route of administration, the correct dose, the best cell population(s), and timing for treatment are parameters that still need to be addressed in order to achieve the goal of complete cardiac regeneration. Despite significant progress, many challenges remain.

Wisp2 disruption represses Cxcr4 expression and inhibits BMSCs homing to injured liver

Liver regeneration/repair is a compensatory regrowth following acute liver failure, and bone marrow-derived mesenchyme stem cell (BMSC) transplantation is an effective therapy that promotes liver regeneration/repair. Wnt1 inducible signaling pathway protein 2 (Wisp2) is highly expressed in BMSCs, however, its function remains unclear. In this work, we used clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein -9 nuclease (CRISPR/Cas9) genome editing technology to knockdown Wisp2 in BMSCs, and these modified cells were then transplanted into rats which were induced by the 2-AAF/PH. By linking the expression of Cas9 to green fluorescent protein (GFP), we tracked BMSCs in the rats. Disruption of Wisp2 inhibited the homing of BMSCs to injured liver and aggravated liver damage as indicated by remarkably high levels of ALT and AST. Moreover, the key factor in BMSC transplantation, C-X-C chemokine receptor type 4 (Cxcr4), was down-regulated in the Wisp2 depleted BMSCs and had a lower expression in the livers of the corresponding rats. By tracing the GFP marker, more BMSCs were observed to differentiate into CD31 positive endothelial cells in the functional Wisp2 cells but less in the Wisp2 gene disrupted cells. In summary, Wisp2 promotes the homing of BMSCs through Cxcr4 related signaling during liver repair in rats.

Mesenchymal Stem Cell Secretome: Toward Cell-Free Therapeutic Strategies in Regenerative Medicine

Earlier research primarily attributed the effects of mesenchymal stem cell (MSC) therapies to their capacity for local engrafting and differentiating into multiple tissue types. However, recent studies have revealed that implanted cells do not survive for long, and that the benefits of MSC therapy could be due to the vast array of bioactive factors they produce, which play an important role in the regulation of key biologic processes. Secretome derivatives, such as conditioned media or exosomes, may present considerable advantages over cells for manufacturing, storage, handling, product shelf life and their potential as a ready-to-go biologic product. Nevertheless, regulatory requirements for manufacturing and quality control will be necessary to establish the safety and efficacy profile of these products. Among MSCs, human uterine cervical stem cells (hUCESCs) may be a good candidate for obtaining secretome-derived products. hUCESCs are obtained by Pap cervical smear, which is a less invasive and painful method than those used for obtaining other MSCs (for example, from bone marrow or adipose tissue). Moreover, due to easy isolation and a high proliferative rate, it is possible to obtain large amounts of hUCESCs or secretome-derived products for research and clinical use.

Preferred M2 Polarization by ASC-Based Hydrogel Accelerated Angiogenesis and Myogenesis in Volumetric Muscle Loss Rats

Volumetric muscle loss (VML) injury resulted from massive muscle defects and diseases for which there are still no effective therapeutic treatments. This study aimed to investigate the effects of rat adipose-derived mesenchymal stem cells (rASCs) and rASCs-conditioned medium- (CM-) based type I collagen hydrogel on macrophage (MP) transition, myogenesis, and vascularization in the rat VML model. Laser Doppler results demonstrated much higher blood flow in the rASC- and CM-based hydrogel groups. qRT-PCR, hematoxylin and eosin, immunofluorescence, and Sirius Red staining manifested that both rASCs and CM-based hydrogel implantation accelerated muscle repair with upregulated angiogenesis and myogenesis, attenuated inflammation while facilitating M2 transition, and decreased the collagen deposition compared with the hydrogel group. In vitro experiments indicated that factors secreted from polarized M2 MPs could accelerate the migration and tube formation capacities of HUVECs. These results suggested that rASCs exerted immunomodulatory effects on MPs which further enhanced the proangiogenic potential on ECs to promote myogenesis and angiogenesis during muscle repair. These fundamental results support further clinical applications of ASCs for muscle loss injury.

Osteogenic differentiation potential of adipose-derived stem cells from ovariectomized mice

OBJECTIVES

Osteoporosis (OP) is a systemic disease caused by imbalance between bone resorption and bone formation, commonly resulting from post-menopausal oestrogen deficiency. Although osteogenic differentiation potential of adipose-derived stem cells (ASCs) has been demonstrated, the effect of OP on osteogenic differentiation of ASCs remains unclear. Here, our work has been designed to compare proliferative capacity and osteogenic differentiation ability of ASCs obtained from osteoporotic mice and normal control mice.

MATERIALS AND METHODS

Twenty 14-week-old female C57BL/6 mice were randomly divided into two groups: one, the ovariectomy (OVX) group (n=10), the other being the sham operated (Sham) group (n=10). ASCs and OP-ASCs were obtained from subcutaneous fat of female inguinal sites. Cells were passaged three times prior to subsequent experimentation. The xCELLigence system was used to monitor cell adhesion and proliferation. Mineralized nodules of differentiated ASCs and OP-ASCs were analysed using Alizarin red staining after osteogenic induction. Expressions of osteogenic-specific genes including osteopontin (Opn) and runt-related transcription factor 2 (Runx2) were assessed by real-time PCR and expression of bone-related proteins was detected by Western blotting.

RESULTS

Numbers of cells in all groups increased steadily for 6 days; rate of cell proliferation in the Sham group was found to be higher than in the OVX group after 48 hours. Mineralized bone nodular structures were significantly more concentrated in the Sham group than in the OVX group by day 21, and mRNA levels of Runx2 in the OVX group were significantly lower than in the Sham group. Transcript levels of genes coding for Opn showed a similar pattern to those of Runx2. Western blot results indicated that protein expression levels of OPN and RUNX2 in the OVX group were lower than those in the Sham group, at each time point.

CONCLUSIONS

These results indicated that the proliferative capacity and osteogenic potential of ASCs were significantly impaired in osteoporotic mice compared to normal controls. However, use of autologous transplantation of modified OP-ASCs for treatment of OP, or combination of composite scaffolds and modified OP-ASCs for repair of osteoporotic bone defects, can overcome shortcomings of other methods.

Comparative analysis of human mesenchymal stem cells from fetal-bone marrow, adipose tissue, and Warton's jelly as sources of cell immunomodulatory therapy

To characterize different tissue MSCs as sources of cell immunomodulatory therapy. Examined the effects of IFN-γ on WJ-MSC and their immunomodulatory function characteristics. We compared human fetal bone marrow (F-BM), adipose tissue (AT), and Warton's Jelly-derived MSCs (WJ-MSCs) for surface antigen expression, differentiation ability, proliferation capacity, clonality, tolerance for aging, gene expression, and whether IFN-γ affected WJ-MSC gene expression, as determined by real time quantitative PCR. Fifteen geneswere examined. We further assess WJ-MSCs-mediated immunomodulatory on peripheral blood mononuclear, stimulated by PHA, IL-2 and CD3Ab after 5 days of co-cultured in a 5:1 ratio (PBMC:MSCs). Examined the effect of WJ-MSCs on the Th1, Th2, Th17 cytokines production and Treg augument. MSCs from different tissues have similar levels of cell surface antigen expression and differentiation ability, while F-BM-MSCs and WJ-MSC had higher rates of cell proliferation and clonality than AD-MSCs. All 15 genes were expressed at similar levels in WJ-MSCs and AD-MSCs (P > 0.05). 9 genes were upregulated in WJ-MSCFor F-MSC, including IL-6, CXCL9, CXCL10, CXCL11, ICAM-1, IDO1, HLA-G5, SDF1A, and NOTCH were down expression, but VCAM-1 was lower expressionin WJ-MSCS. After IFN-γ treatment, 7 genes were upregulated in WJ-MSC, including chemokine ligands CXCL9, CXCL10 and CXCL11, and the adhesion protein VCAM1and ICAM1. Additionally, immunosuppressive factors, such as HLA-G and IDO were both increased. When cocultured with peripheral blood mononuclear, WJ-MSCs showed an immunosuppressive function by inhibit the proliferative response of Th1 and Th17 but augment Th2 and Treg. Primed WJ-MSCs by IFNγ caused a greater reduction in IFNγ and TNFα than untreated WJ-MSCs, also the effect on augument in Treg and inhibit Th17 (P < 0.01). Our results demonstrate that primitive F-BM-MSCs and WJ-MSCs have biological advantages as compared to adult cells, WJ-MSCs have a gene expression pattern similar to AT-MSCs but not F-BM MSCs, and that inflammatory stimuli regulate gene expression in WJ-MSCs. WJ-MSC showed the immunosuppressive function in co-cultured system with PBMC, and IFNγ can promoted the immunosuppressive function.

Adult Stem Cell Therapy for Stroke: Challenges and Progress

Stroke is one of the leading causes of death and physical disability among adults. It has been 15 years since clinical trials of stem cell therapy in patients with stroke have been conducted using adult stem cells like mesenchymal stem cells and bone marrow mononuclear cells. Results of randomized controlled trials showed that adult stem cell therapy was safe but its efficacy was modest, underscoring the need for new stem cell therapy strategies. The primary limitations of current stem cell therapies include (a) the limited source of engraftable stem cells, (b) the presence of optimal time window for stem cell therapies, (c) inherited limitation of stem cells in terms of growth, trophic support, and differentiation potential, and (d) possible transplanted cell-mediated adverse effects, such as tumor formation. Here, we discuss recent advances that overcome these hurdles in adult stem cell therapy for stroke.

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.

Unveiling the Differences of Secretome of Human Bone Marrow Mesenchymal Stem Cells, Adipose Tissue-Derived Stem Cells, and Human Umbilical Cord Perivascular Cells: A Proteomic Analysis

The use of human mesenchymal stem cells (hMSCs) has emerged as a possible therapeutic strategy for CNS-related conditions. Research in the last decade strongly suggests that MSC-mediated benefits are closely related with their secretome. Studies published in recent years have shown that the secretome of hMSCs isolated from different tissue sources may present significant variation. With this in mind, the present work performed a comparative proteomic-based analysis through mass spectrometry on the secretome of hMSCs derived from bone marrow (BMSCs), adipose tissue (ASCs), and human umbilical cord perivascular cells (HUCPVCs). The results revealed that BMSCs, ASCs, and HUCPVCs differed in their secretion of neurotrophic, neurogenic, axon guidance, axon growth, and neurodifferentiative proteins, as well as proteins with neuroprotective actions against oxidative stress, apoptosis, and excitotoxicity, which have been shown to be involved in several CNS disorder/injury processes. Although important changes were observed within the secretome of the cell populations that were analyzed, all cell populations shared the capability of secreting important neuroregulatory molecules. The difference in their secretion pattern may indicate that their secretome is specific to a condition of the CNS. Nevertheless, the confirmation that the secretome of MSCs isolated from different tissue sources is rich in neuroregulatory molecules represents an important asset not only for the development of future neuroregenerative strategies but also for their use as a therapeutic option for human clinical trials.

Adipose-Derived Regenerative Cells Promote Tendon-Bone Healing in a Rabbit Model

PURPOSE

To evaluate the therapeutic effect of adipose-derived regenerative cell (ADRC) administration on tendon-bone healing in a rabbit anterior cruciate ligament (ACL) reconstruction model.

METHODS

ACL reconstruction with semitendinosus tendon autograft was performed in the right knees of adult white rabbits. Eighty rabbits were divided into 2 groups: the treatment group, in which the graft was coated with ADRCs mixed in a fibrin glue carrier during surgery, and the control group, in which the graft was coated with fibrin glue only. At 2, 4, 6, 8, and 12 weeks postoperatively, 8 rabbits were killed in each group. Three were used for histologic evaluation at the tendon-bone interface and 5 for biomechanical examination.

RESULTS

On histologic analysis, chondroid cells appeared more orderly and more regular in size and shape and Sharpey-like fibers, which connected the tendon graft and bone tissue, appeared earlier in ADRC-treated tissues than in control tissues. On biomechanical analysis, the ultimate failure load in the ADRC-treated group was significantly greater than that in the control group at 2 weeks (29.5 ± 7.2 N v 20.9 ± 2.7 N, P = .016) and 4 weeks (32.3 ± 3.9 N v 22.8 ± 5.4 N, P = .016). Stiffness was significantly higher in the ADRC-treated group than in the control group at 6 weeks (21.7 ± 5.9 N/mm v 12.6 ± 4.9 N/mm, P = .037). Although the ultimate failure load and stiffness of the ADRC-treated limbs were higher than those of the limbs in the control group at 8 and 12 weeks, these differences were not significant.

CONCLUSIONS

Local administration of ADRCs promoted the early healing process at the tendon-bone junction, both histologically and mechanically, in a rabbit ACL reconstruction model.

CLINICAL RELEVANCE

ADRCs could be used to enhance graft healing in ACL reconstruction.

Impact of Enhanced Production of Endogenous Heme Oxygenase-1 by Pitavastatin on Survival and Functional Activities of Bone Marrow-derived Mesenchymal Stem Cells

Although mesenchymal stem cells (MSCs) have a therapeutic potential for the repair of tissue injuries, their poor viability in damaged tissue limits their effectiveness. Statins can induce an increased production of heme oxygenase-1 (HO-1), which may prevent this detrimental effect in MSCs. We investigated the protective effect of statin-induced overexpression of HO-1 by examining changes in gene expression and function in MSCs after pitavastatin treatment. The relative expression of the HO-1 and endothelial nitric oxide synthase genes in MSCs was significantly increased after treatment with pitavastatin (MSCs). Immunocytological analysis showed that MSCs also stained with phospho-Akt. After exposure to oxidative stress, MSCs showed increased resistance to induced cell death compared with control MSCs. Under serum starvation conditions, MSCs treated with 1 μM pitavastatin showed enhanced cell proliferation and a marked increase in vascular endothelial growth factor production compared with control MSCs. Interestingly, MSCs showed enhanced tube formation under both normoxia and hypoxia. These results demonstrate that pitavastatin can enhance endogenous HO-1 expression in MSCs, which may protect the cells into the environment of oxidative stress with partial activation of endothelial nitric oxide synthase and Akt phosphorylation.

Transplantation of Immortalized CD34+ and CD34- Adipose-Derived Stem Cells Improve Cardiac Function and Mitigate Systemic Pro-Inflammatory Responses

Adipose-derived stem cells (ADSCs) have the potential to differentiate into various cell lineages and they are easily obtainable from patients, which makes them a promising candidate for cell therapy. However, a drawback is their limited life span during in vitro culture. Therefore, hTERT-immortalized CD34+ and CD34- mouse ADSC lines (mADSCs^hTERT) tagged with GFP were established. We evaluated the proliferation capacity, multi-differentiation potential, and secretory profiles of CD34+ and CD34- mADSCs^hTERTin vitro, as well as their effects on cardiac function and systemic inflammation following transplantation into a rat model of acute myocardial infarction (AMI) to assess whether these cells could be used as a novel cell source for regeneration therapy in the cardiovascular field. CD34+ and CD34- mADSCs^hTERT demonstrated phenotypic characteristics and multi-differentiation potentials similar to those of primary mADSCs. CD34+ mADSCs^hTERT exhibited a higher proliferation ability compared to CD34- mADSCs^hTERT, whereas CD34- mADSCs^hTERT showed a higher osteogenic differentiation potential compared to CD34+ mADSCs^hTERT. Primary mADSCs, CD34+, and CD34- mADSCs^hTERT primarily secreted EGF, TGF-β1, IGF-1, IGF-2, MCP-1, and HGFR. CD34+ mADSCs^hTERT had higher secretion of VEGF and SDF-1 compared to CD34- mADSCs^hTERT. IL-6 secretion was severely reduced in both CD34+ and CD34- mADSCs^hTERT compared to primary mADSCs. Transplantation of CD34+ and CD34- mADSCs^hTERT significantly improved the left ventricular ejection fraction and reduced infarct size compared to AMI-induced rats after 28 days. At 28 days after transplantation, engraftment of CD34+ and CD34- mADSCs^hTERT was confirmed by positive Y chromosome staining, and differentiation of CD34+ and CD34- mADSCs^hTERT into endothelial cells was found in the infarcted myocardium. Significant decreases were observed in circulating IL-6 levels in CD34+ and CD34- mADSCs^hTERT groups compared to the AMI-induced control group. Transplantation of CD34- mADSCs^hTERT significantly reduced circulating MCP-1 levels compared to the AMI control and CD34+ mADSCs^hTERT groups. GFP-tagged CD34+ and CD34- mADSCs^hTERT are valuable resources for cell differentiation studies in vitro as well as for regeneration therapy in vivo.

Ultrasound-Assisted Liposuction Does Not Compromise the Regenerative Potential of Adipose-Derived Stem Cells

The regenerative abilities of adipose-derived mesenchymal stem cells (ASCs) harvested via a third-generation ultrasound-assisted liposuction (UAL) device versus ASCs obtained via standard suction-assisted lipoaspiration were evaluated. ASC yield and viability, and expression of most osteogenic, adipogenic, and key regenerative genes were equivalent between the two methods. Cells harvested via UAL showed comparable abilities to enhance cutaneous regeneration and appear suitable for cell therapy and tissue engineering applications.

Human mesenchymal stem cells (MSCs) have recently become a focus of regenerative medicine, both for their multilineage differentiation capacity and their excretion of proregenerative cytokines. Adipose-derived mesenchymal stem cells (ASCs) are of particular interest because of their abundance in fat tissue and the ease of harvest via liposuction. However, little is known about the impact of different liposuction methods on the functionality of ASCs. Here we evaluate the regenerative abilities of ASCs harvested via a third-generation ultrasound-assisted liposuction (UAL) device versus ASCs obtained via standard suction-assisted lipoaspiration (SAL). Lipoaspirates were sorted using fluorescent assisted cell sorting based on an established surface-marker profile (CD34+/CD31−/CD45−), to obtain viable ASCs. Yield and viability were compared and the differentiation capacities of the ASCs were assessed. Finally, the regenerative potential of ASCs was examined using an in vivo model of tissue regeneration. UAL- and SAL-derived samples demonstrated equivalent ASC yield and viability, and UAL ASCs were not impaired in their osteogenic, adipogenic, or chondrogenic differentiation capacity. Equally, quantitative real-time polymerase chain reaction showed comparable expression of most osteogenic, adipogenic, and key regenerative genes between both ASC groups. Cutaneous regeneration and neovascularization were significantly enhanced in mice treated with ASCs obtained by either UAL or SAL compared with controls, but there were no significant differences in healing between cell-therapy groups. We conclude that UAL is a successful method of obtaining fully functional ASCs for regenerative medicine purposes. Cells harvested with this alternative approach to liposuction are suitable for cell therapy and tissue engineering applications.

Significance

Adipose-derived mesenchymal stem cells (ASCs) are an appealing source of therapeutic progenitor cells because of their multipotency, diverse cytokine profile, and ease of harvest via liposuction. Alternative approaches to classical suction-assisted liposuction are gaining popularity; however, little evidence exists regarding the impact of different liposuction methods on the regenerative functionality of ASCs. Human ASC characteristics and regenerative capacity were assessed when harvested via ultrasound-assisted (UAL) versus standard suction-assisted liposuction. ASCs obtained via UAL were of equal quality when directly compared with the current gold standard harvest method. UAL is an adjunctive source of fully functional mesenchymal stem cells for applications in basic research and clinical therapy.

Trophic factors from adipose tissue-derived multi-lineage progenitor cells promote cytodifferentiation of periodontal ligament cells

Stem and progenitor cells are currently being investigated for their applicability in cell-based therapy for periodontal tissue regeneration. We recently demonstrated that the transplantation of adipose tissue-derived multi-lineage progenitor cells (ADMPCs) enhances periodontal tissue regeneration in beagle dogs. However, the molecular mechanisms by which transplanted ADMPCs induce periodontal tissue regeneration remain to be elucidated. In this study, trophic factors released by ADMPCs were examined for their paracrine effects on human periodontal ligament cell (HPDL) function. ADMPC conditioned medium (ADMPC-CM) up-regulated osteoblastic gene expression, alkaline phosphatase activity and calcified nodule formation in HPDLs, but did not significantly affect their proliferative response. ADMPCs secreted a number of growth factors, including insulin-like growth factor binding protein 6 (IGFBP6), hepatocyte growth factor and vascular endothelial growth factor. Among these, IGFBP6 was most highly expressed. Interestingly, the positive effects of ADMPC-CM on HPDL differentiation were significantly suppressed by transfecting ADMPCs with IGFBP6 siRNA. Our results suggest that ADMPCs transplanted into a defect in periodontal tissue release trophic factors that can stimulate the differentiation of HPDLs to mineralized tissue-forming cells, such as osteoblasts and cementoblasts. IGFBP6 may play crucial roles in ADMPC-induced periodontal regeneration.

Adipose Tissue-Derived Mesenchymal Stem Cells Attenuate Pulmonary Infection Caused by Pseudomonas aeruginosa via Inhibiting Overproduction of Prostaglandin E2

RATIONALE

New strategies for treating Pseudomonas aeruginosa pulmonary infection are urgently needed. Adipose tissue-derived mesenchymal stem cells (ASCs) may have a potential therapeutic role in P. aeruginosa-induced pulmonary infection.

METHODS

The therapeutic and mechanistic effects of ASCs on P. aeruginosa pulmonary infection were evaluated in a murine model of P. aeruginosa pneumonia.

RESULTS

ASCs exhibited protective effects against P. aeruginosa pulmonary infection, evidenced by reduced bacterial burdens, inhibition of alveolar neutrophil accumulation, decreased levels of myeloperoxidase, macrophage inflammatory protein-2 and total proteins in broncho-alveolar lavage fluid (BALF), and attenuated severity of lung injury. ASCs had no effects on BALF and serum levels of keratinocyte growth factor or Ang-1. ASCs had no effects on the levels of insulin growth factor 1 (IGF-1) in BALF, but increased IGF-1 levels in serum. ASCs inhibited the overproduction of prostaglandin E2 (PGE2 ) by decreasing the expression of cyclooxygenase-2 (COX2) and enhancing the expression of 15-PGDH. In addition, the addition of exogenous PGE2 with ASCs abolished many of the protective effects of ASCs, and administrating PGE2 alone exacerbated lung infection. By inhibiting production of PGE2 , ASCs improved phagocytosis and the bactericidal properties of macrophages. Furthermore suppressing PGE2 signaling by COX2 inhibition or EP2 inhibition exhibited protective effects against pulmonary infection as well.

CONCLUSIONS

In a murine model of P. aeruginosa pneumonia, ASCs exhibited protective effects by inhibiting production of PGE2 , which subsequently improved phagocytosis and the bactericidal properties of macrophages. ASCs may provide a new strategy for managing pulmonary infection caused by P. aeruginosa.

Comparative analysis of human mesenchymal stem cells from bone marrow and adipose tissue under xeno-free conditions for cell therapy

INTRODUCTION

Mesenchymal stem cells (MSCs) are promising candidates for cell-based therapies. Human platelet lysate represents an efficient alternative to fetal bovine serum for clinical-scale expansion of MSCs. Different media used in culture processes should maintain the biological characteristics of MSCs during multiple passages. However, bone marrow-derived MSCs and adipose tissue-derived MSCs have not yet been directly compared with each other under human platelet lysate conditions. This study aims to conduct a direct head-to-head comparison of the biological characteristics of the two types of MSCs under human platelet lysate-supplemented culture conditions for their ability to be used in regenerative medicine applications.

METHODS

The bone marrow- and adipose tissue-derived MSCs were cultured under human platelet lysate conditions and their biological characteristics evaluated for cell therapy (morphology, immunophenotype, colony-forming unit-fibroblast efficiency, proliferation capacity, potential for mesodermal differentiation, secreted proteins, and immunomodulatory effects).

RESULTS

Under human platelet lysate-supplemented culture conditions, bone marrow- and adipose tissue-derived MSCs exhibited similar fibroblast-like morphology and expression patterns of surface markers. Adipose tissue-derived MSCs had greater proliferative potential than bone marrow-derived MSCs, while no significantly difference in colony efficiency were observed between the two types of cells. However, bone marrow-derived MSCs possessed higher capacity toward osteogenic and chondrogenic differentiation compared with adipose tissue-derived MSCs, while similar adipogenic differentiation potential wase observed between the two types of cells. There were some differences between bone marrow- and adipose tissue-derived MSCs for several secreted proteins, such as cytokine (interferon-γ), growth factors (basic fibroblast growth factor, hepatocyte growth factor, and insulin-like growth factor-1), and chemokine (stem cell-derived factor-1). Adipose tissue-derived MSCs had more potent immunomodulatory effects than bone marrow-derived MSCs.

CONCLUSIONS

Adipose tissue-derived MSCs have biological advantages in the proliferative capacity, secreted proteins (basic fibroblast growth factor, interferon-γ, and insulin-like growth factor-1), and immunomodulatory effects, but bone marrow-derived MSCs have advantages in osteogenic and chondrogenic differentiation potential and secreted proteins (stem cell-derived factor-1 and hepatocyte growth factor); these biological advantages should be considered systematically when choosing the MSC source for specific clinical application.