c-Kit-Positive Adipose Tissue-Derived Mesenchymal Stem Cells Promote the Growth and Angiogenesis of Breast Cancer

Loss of c-Kit in Endothelial Cells Protects against Hindlimb Ischemia

BACKGROUND

Critical limb ischemia (CLI) is the end stage of peripheral artery disease (PAD), and around 30% of CLI patients are ineligible for current treatments. The angiogenic benefits of c-Kit have been reported in the ischemia scenario; however, the present study demonstrates the effects of specific endothelial c-Kit signaling in arteriogenesis during hindlimb ischemia.

METHODS

We created conditional knockout mouse models that decrease c-Kit (c-Kit VE-Cadherin CreERT2-c-Kit) or its ligand (SCF VE-Cadherin CreERT2-SCF) specifically in endothelial cells (ECs) after tamoxifen treatment. These mice and a control group (wild-type VE-Cadherin CreERT2-WT) were subjected to hindlimb ischemia or aortic crush to evaluate perfusion/arteriogenesis and endothelial barrier permeability, respectively.

RESULTS

Our data confirmed the lower gene expression of c-Kit and SCF in the ECs of c-Kit and SCF mice, respectively. In addition, we confirmed the lower percentage of ECs positive for c-Kit in c-Kit mice. Further, we found that c-Kit and SCF mice had better limb perfusion and arteriogenesis compared to WT mice. We also demonstrated that c-Kit and SCF mice had a preserved endothelial barrier after aortic crush compared to WT.

CONCLUSIONS

Our data demonstrate the deleterious effects of endothelial SCF/c-Kit signaling on arteriogenesis and endothelial barrier integrity.

The role of mesenchymal stem cell transplantation for ischemic stroke and recent research developments

Ischemic stroke is a common cerebrovascular disease that seriously affects human health. However, most patients do not practice self-care and cannot rely on the current clinical treatment for guaranteed functional recovery. Stem cell transplantation is an emerging treatment studied in various central nervous system diseases. More importantly, animal studies show that transplantation of mesenchymal stem cells (MSCs) can alleviate neurological deficits and bring hope to patients suffering from ischemic stroke. This paper reviews the biological characteristics of MSCs and discusses the mechanism and progression of MSC transplantation to provide new therapeutic directions for ischemic stroke.

The effect of obesity on adipose-derived stromal cells and adipose tissue and their impact on cancer

The significant increase in the incidence of obesity represents the next global health crisis. As a result, scientific research has focused on gaining deeper insights into obesity and adipose tissue biology. As a result of the excessive accumulation of adipose tissue, obesity results from hyperplasia and hypertrophy within the adipose tissue. The functional alterations in the adipose tissue are a confounding contributing factor to many diseases, including cancer. The increased incidence and aggressiveness of several cancers, including colorectal, postmenopausal breast, endometrial, prostate, esophageal, hematological, malignant melanoma, and renal carcinomas, result from obesity as a contributing factor. The increased morbidity and mortality of obesity-associated cancers are attributable to increased hormones, adipokines, and cytokines produced by the adipose tissue. The increased adipose tissue levels observed in obese patients result in more adipose stromal/stem cells (ASCs) distributed throughout the body. ASCs have been shown to impact cancer progression in vitro and in preclinical animal models. ASCs influence tumor biology via multiple mechanisms, including the increased recruitment of ASCs to the tumor site and increased production of cytokines and growth factors by ASCs and other cells within the tumor stroma. Emerging evidence indicates that obesity induces alterations in the biological properties of ASCs, subsequently leading to enhanced tumorigenesis and metastasis of cancer cells. As the focus of this review is the interaction and impact of ASCs on cancer, the presentation is limited to preclinical data generated on cancers in which there is a demonstrated role for ASCs, such as postmenopausal breast, colorectal, prostate, ovarian, multiple myeloma, osteosarcoma, cervical, bladder, and gastrointestinal cancers. Our group has investigated the interactions between obesity and breast cancer and the mechanisms that regulate ASCs and adipocytes in these different contexts through interactions between cancer cells, immune cells, and other cell types present in the tumor microenvironment (TME) are discussed. The reciprocal and circular feedback loop between obesity and ASCs and the mechanisms by which ASCs from obese patients alter the biology of cancer cells and enhance tumorigenesis will be discussed. At present, the evidence for ASCs directly influencing human tumor growth is somewhat limited, though recent clinical studies suggest there may be some link.

Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells, Obesity and the Tumor Microenvironment of Breast Cancer

Breast cancer is the most frequently diagnosed cancer and a common cause of cancer-related death in women. It is well recognized that obesity is associated with an enhanced risk of more aggressive breast cancer as well as reduced patient survival. Adipose tissue is the major microenvironment of breast cancer. Obesity changes the composition, structure, and function of adipose tissue, which is associated with inflammation and metabolic dysfunction. Interestingly, adipose tissue is rich in ASCs/MSCs, and obesity alters the properties and functions of these cells. As a key component of the mammary stroma, ASCs play essential roles in the breast cancer microenvironment. The crosstalk between ASCs and breast cancer cells is multilateral and can occur both directly through cell-cell contact and indirectly via the secretome released by ASC/MSC, which is considered to be the main effector of their supportive, angiogenic, and immunomodulatory functions. In this narrative review, we aim to address the impact of obesity on ASCs/MSCs, summarize the current knowledge regarding the potential pathological roles of ASCs/MSCs in the development of breast cancer, discuss related molecular mechanisms, underline the possible clinical significance, and highlight related research perspectives. In particular, we underscore the roles of ASCs/MSCs in breast cancer cell progression, including proliferation and survival, angiogenesis, migration and invasion, the epithelial-mesenchymal transition, cancer stem cell development, immune evasion, therapy resistance, and the potential impact of breast cancer cells on ASCS/MSCs by educating them to become cancer-associated fibroblasts. We conclude that ASCs/MSCs, especially obese ASCs/MSCs, may be key players in the breast cancer microenvironment. Targeting these cells may provide a new path of effective breast cancer treatment.

MAPK/ERK-CBP-RFPL-3 Mediates Adipose-Derived Stem Cell-Induced Tumor Growth in Breast Cancer Cells by Activating Telomerase Reverse Transcriptase Expression

Adipose-derived stem cells (ASCs) improve the self-renewal and survival of fat grafts in breast reconstruction after oncology surgery. However, ASCs have also been found to enhance breast cancer growth, and its role in tumor proliferation remains largely elusive. Here, we explored a novel mechanism that mediates hTERT reactivation during ASC-induced tumor growth in breast cancer cells. In this study, we found the proliferative ability of breast cancer cells markedly increased with ASC coculture. To explore the molecular mechanism, we treated cells with anibody/inhibitor and found that the activation of MEK-ERK pathway was triggered in breast cancer cells by SCF secreted from ASCs, leading to the nuclear recruitment of CBP. As a coactivator of hTERT, CBP subsequently coordinated with RFPL-3 upregulated hTERT transcription and telomerase activity. The inhibition of CBP and RFPL-3 abrogated the activation of hTERT transcription and the promotion of proliferation in breast cancer cells with cocultured ASCs in vitro and in vivo. Collectively, our study findings indicated that CBP coordination with RFPL-3 promotes ASC-induced breast cancer cell proliferation by anchoring to the hTERT promoter and upregulating telomerase activity, which is activated by the MAPK/ERK pathway.

Survivin drives tumor-associated macrophage reprogramming: a novel mechanism with potential impact for obesity

PURPOSE

Recent studies point to adipose-derived stem cells (ASCs) as a link between obesity and cancer. We aimed to determine whether survivin, which is highly secreted by ASCs from subjects with obesity, might drive a pro-tumoral phenotype in macrophages.

METHODS

The effect of ASC conditioned medium on the macrophage phenotype was assessed by expression studies. Survivin intracellular localization and internalization were examined by subcellular fractionation and immunofluorescence, respectively. Loss- and gain-of-function studies were performed using adenoviral vectors, and gene expression patterns, migration and invasion capacities of cancer cells were examined. Heterotypic cultures of ASCs, macrophages and cancer cells were established to mimic the tumor microenvironment. Survivin-blocking experiments were used to determine the impact of survivin on both macrophages and cancer cells. Immunohistochemical analysis of survivin was performed in macrophages from ascitic fluids of cancer patients and healthy controls.

RESULTS

We found that obese-derived ASCs induced a phenotypic switch in macrophages characterized by the expression of both pro- and anti-inflammatory markers. Macrophages were found to internalize extracellular survivin, generating hybrid macrophages with a tumor-associated phenotype that included secretion of survivin. Exogenous expression of survivin in macrophages generated a similar phenotype and enhanced the malignant characteristics of cancer cells by a mechanism dependent on survivin phosphorylation at threonine 34. Survivin secreted by both ASCs from subjects with obesity and tumor-associated macrophages synergistically boosted the malignancy of cancer cells. Importantly, survivin was mainly detected in ascites-associated macrophages from patients with a malignant diagnosis.

CONCLUSION

Our data indicate that survivin may serve as a molecular link between obesity and cancer and as a novel marker for tumor-associated macrophages.

Does C-C Motif Chemokine Ligand 2 (CCL2) Link Obesity to a Pro-Inflammatory State?

The mechanisms of how obesity contributes to the development of cardio-metabolic diseases are not entirely understood. Obesity is frequently associated with adipose tissue dysfunction, characterized by, e.g., adipocyte hypertrophy, ectopic fat accumulation, immune cell infiltration, and the altered secretion of adipokines. Factors secreted from adipose tissue may induce and/or maintain a local and systemic low-grade activation of the innate immune system. Attraction of macrophages into adipose tissue and altered crosstalk between macrophages, adipocytes, and other cells of adipose tissue are symptoms of metabolic inflammation. Among several secreted factors attracting immune cells to adipose tissue, chemotactic C-C motif chemokine ligand 2 (CCL2) (also described as monocyte chemoattractant protein-1 (MCP-1)) has been shown to play a crucial role in adipose tissue macrophage infiltration. In this review, we aimed to summarize and discuss the current knowledge on CCL2 with a focus on its role in linking obesity to cardio-metabolic diseases.

The Proliferation and Differentiation of Adipose-Derived Stem Cells in Neovascularization and Angiogenesis

Neovascularization and angiogenesis are vital processes in the repair of damaged tissue, creating new blood vessel networks and increasing oxygen and nutrient supply for regeneration. The importance of Adipose-derived Mesenchymal Stem Cells (ASCs) contained in the adipose tissue surrounding blood vessel networks to these processes remains unknown and the exact mechanisms responsible for directing adipogenic cell fate remain to be discovered. As adipose tissue contains a heterogenous population of partially differentiated cells of adipocyte lineage; tissue repair, angiogenesis and neovascularization may be closely linked to the function of ASCs in a complex relationship. This review aims to investigate the link between ASCs and angiogenesis/neovascularization, with references to current studies. The molecular mechanisms of these processes, as well as ASC differentiation and proliferation are described in detail. ASCs may differentiate into endothelial cells during neovascularization; however, recent clinical trials have suggested that ASCs may also stimulate angiogenesis and neovascularization indirectly through the release of paracrine factors.

Rat Olfactory Mucosa Mesenchymal Stem/Stromal Cells (OM-MSCs): A Characterization Study

Stem/stromal cell-based therapies are a branch of regenerative medicine and stand as an attractive option to promote the repair of damaged or dysfunctional tissues and organs. Olfactory mucosa mesenchymal stem/stromal cells have been regarded as a promising tool in regenerative therapies because of their several favorable properties such as multipotency, high proliferation rate, helpful location, and few associated ethical issues. These cells are easily accessible in the nasal cavity of most mammals, including the rat, can be easily applied in autologous treatments, and do not cope with most of the obstacles associated with the use of other stem cells. Despite this, its application in preclinical trials and in both human and animal patients is still limited because of the small number of studies performed so far and to the nonexistence of a standard and unambiguous protocol for collection, isolation, and therapeutic application. In the present work a validation of a protocol for isolation, culture, expansion, freezing, and thawing of olfactory mucosa mesenchymal stem/stromal cells was performed, applied to the rat model, as well as a biological characterization of these cells. To investigate the therapeutic potential of OM-MSCs and their eventual safe application in preclinical trials, the main characteristics of OMSC stemness were addressed.

Impact of the Different Preparation Methods to Obtain Human Adipose-Derived Stromal Vascular Fraction Cells (AD-SVFs) and Human Adipose-Derived Mesenchymal Stem Cells (AD-MSCs): Enzymatic Digestion Versus Mechanical Centrifugation

Autologous therapies using adipose-derived stromal vascular fraction (AD-SVFs) and adult adipose-derived mesenchymal stem cells (AD-MSCs) warrant careful preparation of the harvested adipose tissue. Currently, no standardized technique for this preparation exists. Processing quantitative standards (PQSs) define manufacturing quantitative variables (such as time, volume, and pressure). Processing qualitative standards (PQLSs) define the quality of the materials and methods in manufacturing. The purpose of the review was to use PQSs and PQLSs to report the in vivo and in vitro results obtained by different processing kits that use different procedures (enzymatic vs. non-enzymatic) to isolate human AD-SVFs/AD-MSCs. PQSs included the volume of fat tissue harvested and reagents used, the time/gravity of centrifugation, and the time, temperature, and tilt level/speed of incubation and/or centrifugation. PQLSs included the use of a collagenase, a processing time of 30 min, kit weight, transparency of the kit components, the maintenance of a closed sterile processing environment, and the use of a small centrifuge and incubating rocker. Using a kit with the PQSs and PQLSs described in this study enables the isolation of AD-MSCs that meet the consensus quality criteria. As the discovery of new critical quality attributes (CQAs) of AD-MSCs evolve with respect to purity and potency, adjustments to these benchmark PQSs and PQLs will hopefully isolate AD-MSCs of various CQAs with greater reproducibility, quality, and safety. Confirmatory studies will no doubt need to be completed.

Adipose-Derived Stem Cells in Cancer Progression: New Perspectives and Opportunities

Growing importance has been attributed to interactions between tumors, the stromal microenvironment and adult mesenchymal stem cells. Adipose-derived stem cells (ASCs) are routinely employed in regenerative medicine and in autologous fat transfer procedures. To date, clinical trials have failed to demonstrate the potential pro-oncogenic role of ASC enrichment. Nevertheless, some pre-clinical studies from in vitro and in vivo models have suggested that ASCs act as a potential tumor promoter for different cancer cell types, and support tumor progression and invasiveness through the activation of several intracellular signals. Interaction with the tumor microenvironment and extracellular matrix remodeling, the exosomal release of pro-oncogenic factors as well as the induction of epithelial-mesenchymal transitions are the most investigated mechanisms. Moreover, ASCs have also demonstrated an elective tumor homing capacity and this tumor-targeting capacity makes them a suitable carrier for anti-cancer drug delivery. New genetic and applied nanotechnologies may help to design promising anti-cancer cell-based approaches through the release of loaded intracellular nanoparticles. These new anti-cancer therapies can more effectively target tumor cells, reaching higher local concentrations even in pharmacological sanctuaries, and thus minimizing systemic adverse drug effects. The potential interplay between ASCs and tumors and potential ASCs-based therapeutic approaches are discussed.

Concise Review: Adipose-Derived Stem Cells (ASCs) and Adipocyte-Secreted Exosomal microRNA (A-SE-miR) Modulate Cancer Growth and proMote Wound Repair

Adipose-derived stem cells (ASCs) have been routinely used from several years in regenerative surgery without any definitive statement about their potential pro-oncogenic or anti-oncogenic role. ASCs has proven to favor tumor progression in several experimental cancer models, playing a central role in regulating tumor invasiveness and metastatic potential through several mechanisms, such as the paracrine release of exosomes containing pro-oncogenic molecules and the induction of epithelial-mesenchymal transition. However, the high secretory activity and the preferential tumor-targeting make also ASCs a potentially suitable vehicle for delivery of new anti-cancer molecules in tumor microenvironment. Nanotechnologies, viral vectors, drug-loaded exosomes, and micro-RNAs (MiR) represent additional new tools that can be applied for cell-mediated drug delivery in a tumor microenvironment. Recent studies revealed that the MiR play important roles in paracrine actions on adipose-resident macrophages, and their dysregulation has been implicated in the pathogenesis of obesity, diabetes, and diabetic complications as wounds. Numerous MiR are present in adipose tissues, actively participating in the regulation of adipogenesis, adipokine secretion, inflammation, and inter-cellular communications in the local tissues. These results provide important insights into Adipocyte-secreted exosomal microRNA (A-SE-MiR) function and they suggest evaluating the potential role of A-SE-MiR in tumor progression, the mechanisms underlying ASCs-cancer cell interplay and clinical safety of ASCs-based therapies.

Adipose-derived stem cell-mediated paclitaxel delivery inhibits breast cancer growth

Breast cancer represents the main malignancy in women and autologous fat grafting is a diffuse procedure in the management of post-surgical breast defects causing patients’ psychosocial problems, with high costs for the public health. Recently, beneficial effects of fat grafting during post-surgical breast reconstruction have been amplified from the enrichment with human adipose-derived stem cells (ASCs) present in the stromal vascular fraction (SVF) of adult adipose tissue isolated during intraoperatory procedures. The major concern about the ASC enrichment during post-surgery breast reconstruction depends on their potential ability to release growth factors and hormones that can promote proliferation of residual or quiescent cancer cells, with the risk of de novo cancer development or recurrence. The recent description that adult stem cells primed in vitro may be vehicle for anti-cancer drug delivery offers a new vision concerning the role of ASCs in breast reconstruction after cancer surgery. Paclitaxel (PTX) is a chemotherapeutic agent acting as a microtubule-stabilizing drug inhibiting cancer cell mitotic activity. We optimized PTX loading and release in cultured ASCs and then analyzed the effects of PTX-loaded ASCs and their conditioned medium on CG5 breast cancer survival, proliferation and apoptosis in vitro, and inCG5 xenograft in vivo. We documented that ASCs can uptake and release PTX in vitro, with slight cytotoxic effects. Interestingly, PTX-loaded ASCs in co-culture, as well as conditioned medium alone, inhibited CG5 cell proliferation and survival in vitro and xenograft tumor growth in vivo. The antitumor effect of PTX-loaded ASCs may offer a new perspective concerning the use of ASCs during breast reconstruction becoming an additional local preventive chemotherapeutic agent against tumor recurrence. However, further experiments in vitro and in vivo are needed to collect more evidence confirming the efficacy and safety in cancer patients.

Relationship between CD44high/CD133high/CD117high cancer stem cells phenotype and Cetuximab and Paclitaxel treatment response in head and neck cancer cell lines

Recent evidence suggests that cancer stem cells (CSCs), a small population of cancer cells that are highly tumourigenic, capable of self-renewal and have the ability to differentiate into cells that constitute the tumor, are the "drivers" of local recurrence and metastatic spread and may be associated with resistant to conventional therapy. The objectives of the study are to identify and characterize two head and neck cancer cell lines with regard CD44high/CD133high/CD117high profile (CSCs) and CD44low/CD133low/CD117low profile (Non-CSCs); to investigate the influence of chemotherapy treatment in CSCs and compare with Non-CSCs; to evaluate CD44 and EGFR gene expression in CSCs. Fluorescent-activated cell sorting (FACS) using specific cell surface marker combination (CD44, CD117 and CD133) was performed to isolate CSCs of Non-CSCs from cell lines. The Wound Healing assay was performed to confirm the presence of CSCs. After, the CSCs subpopulation and Non-CSCs were cultured and exposed for 24 h to Cetuximab and Paclitaxel treatment, separately. Cell proliferation was determined by MTS assay. CD44 and EGFR gene expression was quantified by quantitative real time PCR (qPCR) using TaqMan® Assay in both subpopulations. CSCs subpopulation untreated were considered as relative expression control. We firstly characterized CSCs in HN13 and HEP-2 cell lines with CD44, CD133 and CD117 biomarkers. We treated CSCs and Non-CSCs subpopulations with Cetuximab and Paclitaxel treatment and found that CSCs subpopulations demonstrated more resistance to Paclitaxel chemoterapy, when compared with Non-CSCs subpopulations of oral cancer cell line. These CSCs subpopulations presented up-regulation of CD44 gene and down-regulation of EGFR gene in oral cancer cell line, and down-regulation of CD44 gene and up-regulation of EGFR gene in laryngeal cancer cell line when compared with Non-CSCs subpopulations. We conclude that the combination of CD44, CD133 and CD117 biomarkers have stem cell properties in both cell lines. CSCs has ability to resist to Paclitaxel treatment in oral cancer cell line. CSCs present high expression of CD44 gene and down expression of EGFR gene in oral cancer cell line. CSCs in laryngeal cell line present down expression of CD44 gene and high expression of EGFR gene when compared with cells without characteristics of cancer stem cells.