Prospective isolation of mesenchymal stem cells from multiple mammalian species using cross-reacting anti-human monoclonal antibodies

Trends of regenerative tissue engineering for oral and maxillofacial reconstruction in veterinary medicine

Oral and maxillofacial (OMF) defects are not limited to humans and are often encountered in other species. Reconstructing significant tissue defects requires an excellent strategy for efficient and cost-effective treatment. In this regard, tissue engineering comprising stem cells, scaffolds, and signaling molecules is emerging as an innovative approach to treating OMF defects in veterinary patients. This review presents a comprehensive overview of OMF defects and tissue engineering principles to establish proper treatment and achieve both hard and soft tissue regeneration in veterinary practice. Moreover, bench-to-bedside future opportunities and challenges of tissue engineering usage are also addressed in this literature review.

Cell surface markers for mesenchymal stem cells related to the skeletal system: A scoping review

Multipotent mesenchymal stromal cells (MSCs) have been described as bone marrow stromal cells, which can form cartilage, bone or hematopoietic supportive stroma. In 2006, the International Society for Cell Therapy (ISCT) established a set of minimal characteristics to define MSCs. According to their criteria, these cells must express CD73, CD90 and CD105 surface markers; however, it is now known they do not represent true stemness epitopes. The objective of the present work was to determine the surface markers for human MSCs associated with skeletal tissue reported in the literature (1994-2021). To this end, we performed a scoping review for hMSCs in axial and appendicular skeleton. Our findings determined the most widely used markers were CD105 (82.9%), CD90 (75.0%) and CD73 (52.0%) for studies performed in vitro as proposed by the ISCT, followed by CD44 (42.1%), CD166 (30.9%), CD29 (27.6%), STRO-1 (17.7%), CD146 (15.1%) and CD271 (7.9%) in bone marrow and cartilage. On the other hand, only 4% of the articles evaluated in situ cell surface markers. Even though most studies use the ISCT criteria, most publications in adult tissues don't evaluate the characteristics that establish a stem cell (self-renewal and differentiation), which will be necessary to distinguish between a stem cell and progenitor populations. Collectively, MSCs require further understanding of their characteristics if they are intended for clinical use.

Manufacturing Mesenchymal Stromal Cells for the Treatment of Osteoarthritis in Canine Patients: Challenges and Recommendations

The recent interest in advanced biologic therapies in veterinary medicine has opened up opportunities for new treatment modalities with considerable clinical potential. Studies with mesenchymal stromal cells (MSCs) from animal species have focused on in vitro characterization (mostly following protocols developed for human application), experimental testing in controlled studies and clinical use in veterinary patients. The ability of MSCs to interact with the inflammatory environment through immunomodulatory and paracrine mechanisms makes them a good candidate for treatment of inflammatory musculoskeletal conditions in canine species. Analysis of existing data shows promising results in the treatment of canine hip dysplasia, osteoarthritis and rupture of the cranial cruciate ligament in both sport and companion animals. Despite the absence of clear regulatory frameworks for veterinary advanced therapy medicinal products, there has been an increase in the number of commercial cell-based products that are available for clinical applications, and currently the commercial use of veterinary MSC products has outpaced basic research on characterization of the cell product. In the absence of quality standards for MSCs for use in canine patients, their safety, clinical efficacy and production standards are uncertain, leading to a risk of poor product consistency. To deliver high-quality MSC products for veterinary use in the future, there are critical issues that need to be addressed. By translating standards and strategies applied in human MSC manufacturing to products for veterinary use, in a collaborative effort between stem cell scientists and veterinary researchers and surgeons, we hope to facilitate the development of quality standards. We point out critical issues that need to be addressed, including a much higher level of attention to cell characterization, manufacturing standards and release criteria. We provide a set of recommendations that will contribute to the standardization of cell manufacturing methods and better quality assurance.

Differences in the biological properties of mesenchymal stromal cells from traumatic temporomandibular joint fibrous and bony ankylosis: a comparative study

The aim of this study was to compare the functional characteristics of mesenchymal stromal cells (MSCs) from a sheep model of traumatic temporomandibular joint (TMJ) fibrous and bony ankylosis. A sheep model of bilateral TMJ trauma-induced fibrous ankylosis on one side and bony ankylosis on the contralateral side was used. MSCs from fibrous ankylosed callus (FA-MSCs) or bony ankylosed callus (BA-MSCs) at weeks 1, 2, 4, and 8 after surgery were isolated and cultured. MSCs derived from the bone marrow of the mandibular condyle (BM-MSCs) were used as controls. The MSCs from the different sources were characterized morphologically, phenotypically, and functionally. Adherence and trilineage differentiation potential were presented in the ovine MSCs. These cell populations highly positively expressed MSC-associated specific markers, namely CD29, CD44, and CD166, but lacked CD31 and CD45 expressions. The BA-MSCs had higher clonogenic and proliferative potentials than the FA-MSCs. The BA-MSCs also showed higher osteogenic and chondrogenic potentials, but lower adipogenic capacity than the FA-MSCs. In addition, the BA-MSCs demonstrated higher chondrogenic, but lower osteogenic capacity than the BM-MSCs. Our study suggests that inhibition of the osteogenic and chondrogenic differentiations of MSCs might be a promising strategy for preventing bony ankylosis in the future.

Visualizing the cancer stem-like properties of canine tumour cells with low proteasome activity

Cancer stem-like cells (CSCs) cause treatment failure in various tumours; however, establishing CSC-targeted therapies has been hampered by difficulties in the identification and isolation of this small sub-population of cells. Recent studies have revealed that tumour cells with low proteasome activity display a CSC phenotype that can be utilized to image CSCs in canines. This study visualizes and reveals the CSC-like properties of tumour cells with low proteasome activity in HMPOS (osteosarcoma) and MegTCC (transitional cell carcinoma), which are canine cell lines. The parent cells were genetically engineered to express ZsGreen1, a fluorescent protein connected to the carboxyl-terminal degron of canine ornithine decarboxylase that accumulates with low proteasome activity (ZsG⁺ cells). ZsG⁺ cells were imaged and the mode of action of this system was confirmed using a proteasome inhibitor (MG-132), which increased the ZsGreen1 fluorescence intensity. The CSC-like properties of ZsG⁺ cells were evaluated on the basis of cell divisions, cell cycle, the expression of CSC markers and tumourigenicity. ZsG⁺ cells underwent asymmetric divisions and had a low percentage of G0/G1 phase cells; moreover, ZsG⁺ cells expressed CSC markers such as CD133 and showed a large tumourigenic capability. In histopathological analysis, ZsG⁺ cells were widely distributed in the tumour samples derived from ZsG⁺ cells and in the proliferative regions of the tumours. The results of this study indicate that visualized canine tumour cells with low proteasome activity have a CSC-like phenotype and that this visualization system can be utilized to identify and isolate canine CSCs.

SSEA-4 Antigen Is Expressed on Rabbit Lymphocyte Subsets

SSEA-4 antigen can be mainly found in embryos and embryonic stem cells. However, its expression has been observed also in adult stem and progenitor cells, or even in some differentiated cells. Moreover, we found a considerable number of SSEA-4 positive (SSEA-4+) cells within the rabbit peripheral blood and bone marrow mononuclear cells (PBMCs and BMMCs) in our previous study. Since no information about such cells can be found anywhere in the literature, the aim of this study was to identify their origin. At first, phenotypic analyses of fresh rabbit PBMCs and BMMCs were performed using flow cytometry and specific antibodies against SSEA-4 and leukocyte subsets. Then, SSEA-4+ were enriched using magnetic activated cell sorting (MACS) and analyzed for their phenotype using qPCR. We found significant SSEA-4+ cell population in PBMCs (~50%) and BMMCs (~20%). All those cells co-expressed CD45 and a majority of them also expressed B-cell marker (IgM; 50% of SSEA-4+ PBMCs and 60% of SSEA-4+ BMMCs). Increased (p < 0.05) expression of SSEA-4, CD45 and B-cell markers (IgM, CD79α and MHCII) were also noticed by qPCR in SSEA-4+ cells enriched via MACS (with efficiency over 80%). Both methods did not detect significant expression of monocyte or T-cell markers. In conclusion, SSEA-4+ cells in rabbit blood and bone marrow are of hematopoietic origin and probably belong to B-lineage cells as possessing the phenotype of B lymphocytes. However, the true function of SSEA-4 antigen in these cells should be explored by further studies.

Small Ruminants and Its Use in Regenerative Medicine: Recent Works and Future Perspectives

Simple Summary

Small ruminants such as sheep and goats have been increasingly used as animal models due to their dimensions, physiology and anatomy identical to those of humans. Their low costs, ease of accommodation, great longevity and easy handling make them advantageous animals to be used in a wide range of research work. Although there is already a lot of scientific literature describing these species, their use still lacks some standardization. The purpose of this review is to summarize the general principles related to the use of small ruminants as animal models for scientific research.

Abstract

Medical and translational scientific research requires the use of animal models as an initial approach to the study of new therapies and treatments, but when the objective is an exploration of translational potentialities, classical models fail to adequately mimic problems in humans. Among the larger animal models that have been explored more intensely in recent decades, small ruminants, namely sheep and goats, have emerged as excellent options. The main advantages associated to the use of these animals in research works are related to their anatomy and dimensions, larger than conventional laboratory animals, but very similar to those of humans in most physiological systems, in addition to their low maintenance and feeding costs, tendency to be docile, long life expectancies and few ethical complications raised in society. The most obvious disadvantages are the significant differences in some systems such as the gastrointestinal, and the reduced amount of data that limits the comparison between works and the validation of the characterization essays. Despite everything, recently these species have been increasingly used as animal models for diseases in different systems, and the results obtained open doors for their more frequent and advantageous use in the future. The purpose of this review is to summarize the general principles related to the use of small ruminants as animal models, with a focus on regenerative medicine, to group the most relevant works and results published recently and to highlight the potentials for the near future in medical research.

Platelet-Derived Growth Factor Stimulated Migration of Bone Marrow Mesenchymal Stem Cells into an Injectable Gelatin-Hydroxyphenyl Propionic Acid Matrix

Bone marrow mesenchymal stem cells (bMSCs) are responsible in the repair of injured tissue through differentiation into multiple cell types and secretion of paracrine factors, and thus have a broad application profile in tissue engineering/regenerative medicine, especially for the musculoskeletal system. The lesion due to injury or disease may be a closed irregular-shaped cavity deep within tissue necessitating an injectable biomaterial permissive of host (endogenous) cell migration, proliferation and differentiation. Gelatin-hydroxyphenyl propionic acid (Gtn-HPA) is a natural biopolymer hydrogel which is covalently cross-linked by horseradish peroxidase (HRP) and hydrogen peroxide (H₂O₂) in situ and can be delivered to the lesion by needle injection. Growth factors and cytokines can be directly incorporated into the gel or into nano- and micro-particles, which can be employed for sustained release of biomolecules while maintaining their bioactivity. In this study, we selected polyelectrolyte complex nanoparticles (PCNs) prepared with dextran sulfate and chitosan as the carrier for platelet-derived growth factor (PDGF)-BB and stromal cell-derived factor (SDF)-1α, which have been tested effectively in recruiting stem cells. Our in vitro results showed a high degree of viability of bMSCs through the process of Gtn-HPA covalent cross-linking gelation. The Gtn-HPA matrix was highly permissive of bMSC migration, proliferation, and differentiation. PDGF-BB (20 ng/mL) directly incorporated into the gel and, alternatively, released from PCNs stimulated bMSC migration and proliferation. There were only small differences in the results for the direct incorporation of PDGF into the gel compared with its release from PCNs, and for increased doses of the growth factor (200 ng/mL and 2 µg/mL). In contrast, SDF-1α elicited an increase in migration and proliferation only when released from PCNs; its effect on migration was notably less than PDGF-BB. The in vitro results demonstrate that PDGF-BB substantially increases migration of bMSCs into Gtn-HPA and their proliferation in the gel, and that these benefits can be derived from incorporation of a relatively low dose of the growth factor directly into the gel. These findings commend the use of Gtn-HPA/PDGF-BB as an injectable therapeutic agent to treat defects in musculoskeletal tissues.

Mesenchymal Stem/Progenitor Cells: The Prospect of Human Clinical Translation

Mesenchymal stem/progenitor cells (MSCs) are key players in regenerative medicine, relying principally on their differentiation/regeneration potential, immunomodulatory properties, paracrine effects, and potent homing ability with minimal if any ethical concerns. Even though multiple preclinical and clinical studies have demonstrated remarkable properties for MSCs, the clinical applicability of MSC-based therapies is still questionable. Several challenges exist that critically hinder a successful clinical translation of MSC-based therapies, including but not limited to heterogeneity of their populations, variability in their quality and quantity, donor-related factors, discrepancies in protocols for isolation, in vitro expansion and premodification, and variability in methods of cell delivery, dosing, and cell homing. Alterations of MSC viability, proliferation, properties, and/or function are also affected by various drugs and chemicals. Moreover, significant safety concerns exist due to possible teratogenic/neoplastic potential and transmission of infectious diseases. Through the current review, we aim to highlight the major challenges facing MSCs' human clinical translation and shed light on the undergoing strategies to overcome them.

Endometrial and Menstrual Blood Mesenchymal Stem/Stromal Cells: Biological Properties and Clinical Application

A highly proliferative mesenchymal stem/stromal cell (MSC) population was recently discovered in the dynamic, cyclically regenerating human endometrium as clonogenic stromal cells that fulfilled the International Society for Cellular Therapy (ISCT) criteria. Specific surface markers enriching for clonogenic endometrial MSC (eMSC), CD140b and CD146 co-expression, and the single marker SUSD2, showed their perivascular identity in the endometrium, including the layer which sheds during menstruation. Indeed, cells with MSC properties have been identified in menstrual fluid and commonly termed menstrual blood stem/stromal cells (MenSC). MenSC are generally retrieved from menstrual fluid as plastic adherent cells, similar to bone marrow MSC (bmMSC). While eMSC and MenSC share several biological features with bmMSC, they also show some differences in immunophenotype, proliferation and differentiation capacities. Here we review the phenotype and functions of eMSC and MenSC, with a focus on recent studies. Similar to other MSC, eMSC and MenSC exert immunomodulatory and anti-inflammatory impacts on key cells of the innate and adaptive immune system. These include macrophages, T cells and NK cells, both in vitro and in small and large animal models. These properties suggest eMSC and MenSC as additional sources of MSC for cell therapies in regenerative medicine as well as immune-mediated disorders and inflammatory diseases. Their easy acquisition via an office-based biopsy or collected from menstrual effluent makes eMSC and MenSC attractive sources of MSC for clinical applications. In preparation for clinical translation, a serum-free culture protocol was established for eMSC which includes a small molecule TGFβ receptor inhibitor that prevents spontaneous differentiation, apoptosis, senescence, maintains the clonogenic SUSD2+ population and enhances their potency, suggesting potential for cell-therapies and regenerative medicine. However, standardization of MenSC isolation protocols and culture conditions are major issues requiring further research to maximize their potential for clinical application. Future research will also address crucial safety aspects of eMSC and MenSC to ensure these protocols produce cell products free from tumorigenicity and toxicity. Although a wealth of data on the biological properties of eMSC and MenSC has recently been published, it will be important to address their mechanism of action in preclinical models of human disease.

Perspective of placenta derived mesenchymal stem cells in acute liver failure

Acute Liver failure (ALF) is a life-threatening disease and is determined by coagulopathy (with INR ≥ 1.5) and hepatic encephalopathy as a result of severe liver injury in patients without preexisting liver disease. Since there are problems with liver transplantation including lack of donors, use of immunosuppressive drugs, and high costs of this process, new therapeutic approaches alongside current treatments are needed. The placenta is a tissue that is normally discarded after childbirth. On the other hand, human placenta is a rich source of mesenchymal stem cells (MSCs), which is easily available, without moral problems, and its derived cells are less affected by age and environmental factors. Therefore, placenta-derived mesenchymal stem cells (PD-MSCs) can be considered as an allogeneic source for liver disease. Considering the studies on MSCs and their effects on various diseases, it can be stated that MSCs are among the most important agents to be used for novel future therapies of liver diseases. In this paper, we will investigate the effects of mesenchymal stem cells through migration and immigration to the site of injury, cell-to-cell contact, immunomodulatory effects, and secretory factors in ALF.

Combined approach for characterization and quality assessment of rabbit bone marrow-derived mesenchymal stem cells intended for gene banking

Rabbit mesenchymal stem cells (rMSCs) are promising agents for the preservation of genetic biodiversity in domestic rabbit breeds. However, rMSCs must meet certain requirements to be used for cryopreservation in animal gene banks. Currently, there are numerous discrepancies in the published data regarding the rMSC phenotype, which may complicate efforts to evaluate their purity and suitability for reuse after cryopreservation in gene and tissue banks. We propose a combined approach (flow cytometry, PCR, differentiation and ultrastructure studies) for the characterization and recovery of rMSCs after cryopreservation. Flow cytometric analyses of rMSCs confirmed the expression of CD29, CD44, vimentin, desmin and α-SMA. RT-PCR revealed the expression of other markers at the mRNA level (SSEA-4, CD73, CD90, CD105, CD146 and CD166). rMSCs showed efficient multilineage differentiation into adipo-, chondro- and osteogenic lineages, SOX2 expression (pluripotency) and typical MSC morphology and ultrastructure. The confirmed rMSCs were subsequently used for cryopreservation. Efficient recovery of rMSCs after cryogenic freezing was demonstrated by high cell viability, normal ultrastructure of reseeded rMSCs, high expression of CD29 and CD44 and lineage differentiation capacity. The proposed combined approach could be used for characterization, cryopreservation and recovery of rMSCs as genetic resources for native rabbit breeds.

Single-Stage Preparation of Human Cartilage Grafts Generated from Bone Marrow-Derived CD271+ Mononuclear Cells

Due to the limited self-healing capacity of articular cartilage, innovative, regenerative approaches are of particular interest. The use of two-stage procedures utilizing in vitro-expanded mesenchymal stromal cells (MSCs) from various cell sources requires good manufacturing practice-compliant production, a process with high demands on time, staffing, and financial resources. In contrast, one- stage procedures are directly available, but need a safe enrichment of potent MSCs. CD271 is a surface marker known to marking the majority of native MSCs in bone marrow (BM). In this study, the feasibility of generating a single-stage cartilage graft of enriched CD271⁺ BM-derived mononuclear cells (MNCs) without in vitro monolayer expansion from eight healthy donors was investigated. Cartilage grafts were generated by magnetic-activated cell sorting and separated cells were directly transferred into collagen type I hydrogels, followed by 3D proliferation and differentiation period of CD271⁺, CD271^-, or unseparated MNCs. CD271⁺ MNCs showed the highest proliferation rate, cell viability, sulfated glycosaminoglycan deposition, and cartilage marker expression compared to the CD271^- or unseparated MNC fractions in 3D culture. Analysis according to the minimal criteria of the International Society for Cellular Therapy highlighted a 66.8-fold enrichment of fibroblast colony-forming units in CD271⁺ MNCs and the only fulfillment of the MSC marker profile compared to unseparated MNCs. In summary, CD271⁺ MNCs are capable of generating adequate articular cartilage grafts presenting high cell viability and notable chondrogenic matrix deposition in a CE-marked collagen type I hydrogel, which can obviate the need for an initial monolayer expansion.

Preterm umbilical cord blood derived mesenchymal stem/stromal cells protect preterm white matter brain development against hypoxia-ischemia

INTRODUCTION

Preterm infants are at high risk for white matter injury and subsequent neurodevelopmental impairments. Mesenchymal stem/stromal cells (MSC) have anti-inflammatory/immunomodulatory actions and are of interest for neural repair in adults and newborns. This study examined the neuroprotective effects of allogeneic MSC, derived from preterm umbilical cord blood (UCB), in a preterm sheep model of white matter injury.

METHODS

Quad-lineage differentiation, clonogenicity and self-renewal ability of UCB-derived MSC were confirmed. Chronically instrumented fetal sheep (0.7 gestation) received either 25 min hypoxia-ischemia (HI) to induce preterm brain injury, or sham-HI. Ten million MSC, or saline, were administered iv to fetuses at 12 h after HI. Fetal brains were collected 10d after HI for histopathology and immunocytochemistry.

RESULTS

HI induced white matter injury, as indicated by a reduction in CNPase-positive myelin fiber density. HI also induced microglial activation (Iba-1) in the periventricular white matter and internal capsule (P < .05 vs control). MSC administration following HI preserved myelination (P < .05), modified microglial activation, and promoted macrophage migration (CD163) and cell proliferation (Ki-67) within cerebral white matter (P < .05). Cerebral CXCL10 concentration was increased following MSC administration (P < .05), which was likely associated with macrophage migration and cell proliferation within the preterm brain. Additionally, MSC administration reduced systemic pro-inflammatory cytokine TNFα at 3d post-HI (P < .05).

CONCLUSIONS

UCB-derived MSC therapy preserved white matter brain structure following preterm HI, mediated by a suppression of microglial activation, promotion of macrophage migration and acceleration of self-repair within the preterm brain. UCB-derived MSC are neuroprotective, acting via peripheral and cerebral anti-inflammatory and immunomodulatory mechanisms.

Performance of marrow stromal cell-seeded small-caliber multilayered vascular graft in a senescent sheep model

Failure of small-caliber grafts, used as bypass or reconstructive grafts in cardiovascular treatments, is often caused by thrombosis and stenosis. We have developed a multilayered, compliant graft with an electrospun heparin-encapsulated core and collagen-chitosan shell. Herein, the performances of acellular and cell-seeded grafts were evaluated in adult sheep for preclinical assessment. Allogeneic ovine marrow stroma cells (MSCs) were uniformly attached to the lumen of cell-seeded grafts. Interposition grafts were used for carotid arteries. Four grafts were tested for each type. Upon implantation, all grafts successfully restored perfusion and rhythmically deformed under pulsatile arterial flow. Weekly ultrasonography and Doppler revealed that all grafts remained patent for perfusion during the course of one-month study. No formation of blood clots or other complications were found. The diameter of graft lumen did not vary significantly over the time or with the graft type, while narrowing at anastomosis and significant thickening of graft wall were found in both types of grafts. More significant neotissue formation was found at anastomotic sections of acellular controls compared to cell-seeded grafts. Results from histological and immunofluorescent analyses revealed moderate intimal hyperplasia (IH) at anastomosis. When compared to cell-seeded grafts, acellular controls presented thicker IH composed of α-smooth muscle actin positive cells and ground substances, which correlated with reduced and more disturbing flow. IH was thickest at anastomosis and tapered off to a minimum in the mid-section. Few PECAM-positive cells appeared on cell-seeded grafts but not acellular controls. Additionally, lesser graft thickening was found in cell-seed grafts, which might be associated with the function of stromal cells in altering the fibrotic process during tissue repair. Results suggest that MSCs held the potential to reduce hyperplasia and improve healing in an aged, large animal model for vascular grafting.

Point-of-care treatment of focal cartilage defects with selected chondrogenic mesenchymal stromal cells-An in vitro proof-of-concept study

Due to the poor self-healing capacities of cartilage, innovative approaches are a major clinical need. The use of in vitro expanded mesenchymal stromal cells (MSCs) in a 2-stage approach is accompanied by cost-, time-, and personnel-intensive good manufacturing practice production. A 1-stage intraoperative procedure could overcome these drawbacks. The aim was to prove the feasibility of a point-of-care concept for the treatment of cartilage lesions using defined MSC subpopulations in a collagen hydrogel without prior MSC monolayer expansion. We tested 4 single marker candidates (MSCA-1, W4A5, CD146, CD271) for their effectiveness of separating colony-forming units of ovine MSCs via magnetic cell separation. The most promising surface marker with regard to the highest enrichment of colony-forming cells was subsequently used to isolate a MSC subpopulation for the direct generation of a cartilage graft composed of a collagen type I hydrogel without the propagation of MSCs in monolayer. We observed that separation with CD271 sustained the highest enrichment of colony-forming units. We then demonstrated the feasibility of generating a cartilage graft with an unsorted bone marrow mononuclear cell fraction and with a characterized CD271 positive MSC subpopulation without the need for a prior cell expansion. A reduced volume of 6.25% of the CD271 positive MSCs was needed to achieve the same results regarding chondrogenesis compared with the unseparated bone marrow mononuclear cell fraction, drastically reducing the number of nonrelevant cells. This study provides a proof-of-concept and reflects the potential of an intraoperative procedure for direct seeding of cartilage grafts with selected CD271 positive cells from bone marrow.

Porcine Wharton's jelly cells distribute throughout the body after intraperitoneal injection

Background

Wharton's jelly cells (WJCs) have multiple differentiation potentials and are easily harvested in large numbers. WJCs are well tolerated in allogeneic environments and there is a growing list of their therapeutic effects. Most therapies require administering large numbers of cells and this is generally accomplished by intravenous injection. Here, we studied the locations of porcine WJCs in immune-competent, allogeneic hosts after intraperitoneal (IP) injection.

Methods

Male porcine WJCs were administered to female neonatal piglets by IP injection. The location of transplanted cells was examined at 6 h, 24 h, and 7 days after administration using confocal microscopy and polymerase chain reaction (PCR). Transplanted cells were also retrieved from the intestines of recipients and were cultured. Previously transplanted cells were identified by fluorescence in-situ hybridization (FISH) using a Y-chromosome probe.

Results

Allogeneic cells were identified in the small and large intestine, stomach, liver, spleen, diaphragm, omentum, kidney, pancreas, mesenteric lymph nodes, heart, lungs, uterus, bladder, and skeletal muscle. Male cells (SRY positive) were found in cultures of cells harvested from the intestinal mucosa 1 week after administration of male porcine WJCs.

Conclusions

Our results show that porcine WJCs distribute widely to the organs in immunocompetent allogeneic hosts after IP administration. They may distribute through the lymphatics initially, and a prominent site of incorporation is the mucosa of the gastrointestinal tract. In that location they could function in the niche of endogenous stem cells and provide secretory products to cells in the tissue damaged by intestinal disease.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0775-7) contains supplementary material, which is available to authorized users.

Identifying the optimum source of mesenchymal stem cells for use in knee surgery

Single sitting procedures where the mononuclear cell fraction is extracted from bone marrow and implanted directly into cartilage and bone defects are becoming more popular as novel treatments for cartilage defects which have, until now had few treatment options. This is on the basis that the mesenchymal stem cells (MSCs) contained within will repair the damaged tissue. This study sought to determine if the femur and tibia could provide equivalent amounts of mesenchymal stem cells, with equivalent viability and proliferative capacity, to that obtained from the gold standard of the pelvis in order to potentially reduce the morbidity associated with these procedures. Bone marrow was extracted from the pelvis, femur, and tibia of human subjects. The mononuclear cell fraction was extracted and cultured in the laboratory. Mesenchymal stem cell populations were assessed using a colony forming unit count. Viability was assessed using a PrestoBlue viability assay. Population doubling number was calculated between the end of passage 0 and passage three to determine the proliferative abilities of the different populations. Finally, the cell surface phenotype of the cells was determined by flow cytometry. The results showed that the pelvis was superior to the femur and tibia in terms of the number of stem cells isolated. There was no statistically significant difference in the phenotype of the cells isolated from different locations. This work shows that when undertaking single sitting procedures, the pelvis remains the optimum source for obtaining MSCs, despite the morbidity associated with bone marrow collection from the pelvis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1868-1875, 2017.

ISOLAMENTO E CULTIVO DE CÉLULAS TRONCO MESENQUIMAIS EXTRAÍDAS DO TECIDO ADIPOSO E DA MEDULA ÓSSEA DE CÃES

Resumo Objetivou-se estabelecer um protocolo para extração, cultivo e expansão de células tronco mesenquimais (CTM), utilizando-se 3,0 mL da medula óssea e 3,0 cm3 de tecido adiposo do subcutâneo de três cães machos com seis meses de idade. As amostras foram processadas e as células extraídas e cultivadas em DMEM. Para comprovação do isolamento de CTM, procedeu-se a caracterização fenotípica e a diferenciação osteogênica, adipogênica e condrogênica. As células isoladas apresentaram morfologia alongada e fusiforme e capacidade de se diferenciar em osteoblastos, adipócitos e condrócitos. A caracterização fenotípica revelou alta expressão de marcadores de CTM CD90 (80,04%) e CD29 (96%) nas células de origem medular e CD90 (60,94%) e CD29 (77,08%) nas de origem adiposa. A expressão de marcadores hematopoiéticos foi baixa tanto nas células de origem medular CD45 (1,45%) e CD34 (1,53%), quanto nas de origem adiposa CD45 (1,45%) e CD34 (1,53%). As modificações e adaptações realizadas nos protocolos clássicos simplificaram o processo e foram eficientes, permitindo o isolamento e cultivo de CTM da medula óssea e do tecido adiposo de cães.

Mesenchymal stromal/stem cell separation methods: concise review

Mesenchymal stem (stromal) cells (MSCs) possess unique biological characteristics such as plasticity, long term self-renewal, secretion of various bioactive molecules and ability of active migration to the diseased tissues that make them unique tool for regenerative medicine, nowadays. Until now MSCs were successfully derived from many tissue sources including bone marrow, umbilical cord, adipose tissue, dental pulp etc. The crucial step prior to their in vitro expansion, banking or potential clinical application is their separation. This review article aims to briefly describe the main MSCs separations techniques currently available, their basic principles, as well as their advantages and limits. In addition the attention is paid to the markers presently applicable for immunoaffinity-based separation of MSCs from different tissues and organs.

Limbal stromal cells derived from porcine tissue demonstrate mesenchymal characteristics in vitro

Limbal stromal cells (LSCs) from the human ocular surface display mesenchymal stromal cell characteristics in vitro. In this study, we isolated cells from the porcine limbal stroma (pLSCs), characterised them, and evaluated their ability to support angiogenesis and the culture of porcine limbal epithelial stem cells (pLESCs). The isolated cells adhered to plastic and grew in monolayers in vitro using serum-supplemented or serum-free medium. The pLSCs demonstrated expression of CD29, and cross-reactivity with anti-human CD45, CD90, CD105, CD146, and HLA-ABC. However, expression of CD105, CD146 and HLA-ABC reduced when cultured in serum-free medium. PLSCs did not undergo adipogenic or osteogenic differentiation, but differentiated towards the chondrogenic lineage. Isolated cells were also co-cultured with human umbilical vein endothelial cells (HUVECs) in star-shaped Poly(ethylene glycol) (starPEG)-heparin hydrogels to assess their pericyte capacity which supported angiogenesis networks of HUVECs. PLSCs supported the three dimensional HUVEC network for 7 days. The isolated cells were further growth-arrested and evaluated as feeder cells for pLESC expansion on silk fibroin membranes, as a potential carrier material for transplantation. PLSCs supported the growth of pLESCs comparably to murine 3T3 cells. In conclusion, although pLSCs were not completely comparable to their human counterpart, they display several mesenchymal-like characteristics in vitro.

Immunophenotypical characterization of canine mesenchymal stem cells from perivisceral and subcutaneous adipose tissue by a species-specific panel of antibodies

Immunophenotypical characterization of mesenchymal stem cells is fundamental for the design and execution of sound experimental and clinical studies. The scarce availability of species-specific antibodies for canine antigens has hampered the immunophenotypical characterization of canine mesenchymal stem cells (MSC). The aim of this study was to select a panel of species-specific direct antibodies readily useful for canine mesenchymal stem cells characterization. They were isolated from perivisceral and subcutaneous adipose tissue samples collected during regular surgeries from 8 dogs. Single color flow cytometric analysis of mesenchymal stem cells (P3) deriving from subcutaneous and perivisceral adipose tissue with a panel of 7 direct anti-canine antibodies revealed two largely homogenous cell populations with a similar pattern: CD29⁺, CD44⁺, CD73⁺, CD90⁺, CD34^-, CD45^- and MHC-II^- with no statistically significant differences among them. Antibody reactivity was demonstrated on canine peripheral blood mononuclear cells. The similarities are reinforced by their in vitro cell morphology, trilineage differentiation ability and RT-PCR analysis (CD90⁺, CD73⁺, CD105⁺, CD44⁺, CD13⁺, CD29⁺, Oct-4⁺ gene and CD31^- and CD45^- expression). Our results report for the first time a comparison between the immunophenotypic profile of canine MSC deriving from perivisceral and subcutaneous adipose tissue. The substantial equivalence between the two populations has practical implication on clinical applications, giving the opportunity to choose the source depending on the patient needs. The results contribute to routine characterization of MSC populations grown in vitro, a mandatory process for the definition of solid and reproducible laboratory and therapeutic procedures.

Invited review: Pre- and postnatal adipose tissue development in farm animals: from stem cells to adipocyte physiology

Both white and brown adipose tissues are recognized to be differently involved in energy metabolism and are also able to secrete a variety of factors called adipokines that are involved in a wide range of physiological and metabolic functions. Brown adipose tissue is predominant around birth, except in pigs. Irrespective of species, white adipose tissue has a large capacity to expand postnatally and is able to adapt to a variety of factors. The aim of this review is to update the cellular and molecular mechanisms associated with pre- and postnatal adipose tissue development with a special focus on pigs and ruminants. In contrast to other tissues, the embryonic origin of adipose cells remains the subject of debate. Adipose cells arise from the recruitment of specific multipotent stem cells/progenitors named adipose tissue-derived stromal cells. Recent studies have highlighted the existence of a variety of those cells being able to differentiate into white, brown or brown-like/beige adipocytes. After commitment to the adipocyte lineage, progenitors undergo large changes in the expression of many genes involved in cell cycle arrest, lipid accumulation and secretory functions. Early nutrition can affect these processes during fetal and perinatal periods and can also influence or pre-determinate later growth of adipose tissue. How these changes may be related to adipose tissue functional maturity around birth and can influence newborn survival is discussed. Altogether, a better knowledge of fetal and postnatal adipose tissue development is important for various aspects of animal production, including neonatal survival, postnatal growth efficiency and health.

Ovine Mesenchymal Stromal Cells: Morphologic, Phenotypic and Functional Characterization for Osteochondral Tissue Engineering

INTRODUCTION

Knowledge of ovine mesenchymal stromal cells (oMSCs) is currently expanding. Tissue engineering combining scaffolding with oMSCs provides promising therapies for the treatment of osteochondral diseases.

PURPOSE

The aim was to isolate and characterize oMSCs from bone marrow aspirates (oBMSCs) and to assess their usefulness for osteochondral repair using β-tricalcium phosphate (bTCP) and type I collagen (Col I) scaffolds.

METHODS

Cells isolated from ovine bone marrow were characterized morphologically, phenotypically, and functionally. oBMSCs were cultured with osteogenic medium on bTCP and Col I scaffolds. The resulting constructs were evaluated by histology, immunohistochemistry and electron microscopy studies. Furthermore, oBMSCs were cultured on Col I scaffolds to develop an in vitro cartilage repair model that was assessed using a modified International Cartilage Research Society (ICRS) II scale.

RESULTS

oBMSCs presented morphology, surface marker pattern and multipotent capacities similar to those of human BMSCs. oBMSCs seeded on Col I gave rise to osteogenic neotissue. Assessment by the modified ICRS II scale revealed that fibrocartilage/hyaline cartilage was obtained in the in vitro repair model.

CONCLUSIONS

The isolated ovine cells were demonstrated to be oBMSCs. oBMSCs cultured on Col I sponges successfully synthesized osteochondral tissue. The data suggest that oBMSCs have potential for use in preclinical models prior to human clinical studies.

Expression of neural cell adhesion molecule and polysialic acid in human bone marrow-derived mesenchymal stromal cells

BACKGROUND

In order to develop novel clinical applications and to gain insights into possible therapeutic mechanisms, detailed molecular characterization of human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) is needed. Neural cell adhesion molecule (NCAM, CD56) is a transmembrane glycoprotein modulating cell-cell and cell-matrix interactions. An additional post-translational modification of NCAM is the α2,8-linked polysialic acid (polySia). Because of its background, NCAM is often considered a marker of neural lineage commitment. Generally, hBM-MSCs are considered to be devoid of NCAM expression, but more rigorous characterization is needed.

METHODS

We have studied NCAM and polySia expression in five hBM-MSC lines at mRNA and protein levels. Cell surface localization was confirmed by immunofluorescence staining and expression frequency in the donor-specific lines by flow cytometry. For the detection of poorly immunogenic polySia, a fluorochrome-tagged catalytically defective enzyme was employed.

RESULTS

All five known NCAM isoforms are expressed in these cells at mRNA level and the three main isoforms are present at protein level. Both polysialyltransferases, generally responsible for NCAM polysialylation, are expressed at mRNA level, but only very few cells express polySia at the cell surface.

CONCLUSIONS

Our results underline the need for a careful control of methods and conditions in the characterization of MSCs. This study shows that, against the generally held view, clinical-grade hBM-MSCs do express NCAM. In contrast, although both polysialyltransferase genes are transcribed in these cells, very few express polySia at the cell surface. NCAM and polySia represent new candidate molecules for influencing MSC interactions.

Estudo comparativo da diferenciação osteogênica das células tronco mesenquimais da medula óssea e do tecido adiposo de cães adultos

Resumo: O objetivo deste estudo foi comparar o potencial osteogênico das células tronco mesenquimais extraídas da medula óssea (CTM-MO) com as do tecido adiposo (CTM-AD) de cães adultos. As células foram caracterizadas fenotipicamente quanto à expressão de CD29, CD90, CD34 e CD45 e submetidas à diferenciação adipogênica e condrogênica por 21 dias e osteogênica por 7, 14 e 21 dias. Foram constituídos quatro grupos: 1) CTM-MO em meio osteogênico, 2) CTM-MO em meio basal, 3) CTM-AD em meio osteogênico e 4) CTM-AD em meio basal. Aos 7, 14 e 21 dias de diferenciação osteogênica as culturas foram submetidas às avaliações da conversão de MTT em formazan, da atividade da fosfatase alcalina (FA), da síntese de colágeno e de matriz mineralizada, avaliação do número de células por campo e foram quantificados os transcritos gênicos para osterix, sialoproteina óssea (BSP), osteonectina (ON) e osteocalcina (OC). Tanto as células extraídas da medula óssea quanto do tecido adiposo mostraram elevada expressão de marcadores para células tronco e baixa expressão de marcadores de células hematopoiéticas (menor que 2%). Além disso, foram capazes de se diferenciar em osteoblastos, condrócitos e adipócitos. As CTM-AD submetidas à diferenciação osteogênica mostraram maior conversão do MTT em formazan que as CTM-MO, sob mesmas condições aos 7 e 21 dias. O número de células por campo, a atividade da FA, a síntese de colágeno e de matriz mineralizada foram superior nas CTM-AD em diferenciação, em relação às CTM-MO sob as mesmas condições, em todos os tempos estudados. As expressões de osterix, BSP e OC foram predominantemente superiores nas CTM-MO diferenciadas, mas a expressão de ON foi superior nas CTM-AD diferenciadas aos 7, 14 e 21 dias. Conclui-se que as CTM-AD apresentam maior potencial osteogênico que as CTM-MO quando extraídas de cães adultos.

Identification and Characterization of Human Endometrial Mesenchymal Stem/Stromal Cells and Their Potential for Cellular Therapy

SummaryHuman endometrium is a highly regenerative tissue, undergoing more than 400 cycles of proliferation, differentiation, and shedding during a woman's reproductive life. Adult stem cells, including mesenchymal stem/stromal cells (MSCs), are likely responsible for the immense cellular turnover in human endometrium. The unique properties of MSCs, including high proliferative ability, self-renewal, differentiation to mesodermal lineages, secretion of angiogenic factors, and many other growth-promoting factors make them useful candidates for cellular therapy and tissue engineering. In this review, we summarize the identification and characterization of newly discovered MSCs from the human endometrium: their properties, the surface markers used for their prospective isolation, their perivascular location in the endometrium, and their potential application in cellular therapies.

SIGNIFICANCE

The endometrium, or the lining of uterus, has recently been identified as a new and accessible source of mesenchymal stem cells, which can be obtained without anesthesia. Endometrial mesenchymal stem cells have comparable properties to bone marrow and adipose tissue mesenchymal stem cells. Endometrial mesenchymal stem cells are purified with known and novel perivascular surface markers and are currently under investigation for their potential use in cellular therapy for several clinical conditions with significant burden of disease.

Endometrial mesenchymal stem cells as a cell based therapy for pelvic organ prolapse

Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, bowel and sexual dysfunction, negatively impacting upon a woman’s quality of life. POP affects 25% of all women and results from childbirth injury. For 19% of all women, surgical reconstructive surgery is required for treatment, often augmented with surgical mesh. The surgical treatment fails in up to 30% of cases or results in adverse effects, such as pain and mesh erosion into the bladder, bowel or vagina. Due to these complications the Food and Drug Administration cautioned against the use of vaginal mesh and several major brands have been recently been withdrawn from market. In this review we will discuss new cell-based approaches being developed for the treatment of POP. Several cell types have been investigated in animal models, including a new source of mesenchymal stem/stromal cells (MSC) derived from human endometrium. The unique characteristics of endometrial MSC, methods for their isolation and purification and steps towards their development for good manufacturing practice production will be described. Animal models that could be used to examine the potential for this approach will also be discussed as will a rodent model showing promise in developing an endometrial MSC-based therapy for POP. The development of a preclinical large animal model for assessing tissue engineering constructs for treating POP will also be mentioned.

Comparative study of equine mesenchymal stem cells from healthy and injured synovial tissues: an in vitro assessment

Background

Bone marrow and adipose tissues are known sources of mesenchymal stem cells (MSCs) in horses; however, synovial tissues might be a promising alternative. The aim of this study was to evaluate phenotypic characteristics and differentiation potential of equine MSCs from synovial fluid (SF) and synovial membrane (SM) of healthy joints (SF-H and SM-H), joints with osteoarthritis (SF-OA and SM-OA) and joints with osteochondritis dissecans (SF-OCD and SM-OCD) to determine the most suitable synovial source for an allogeneic therapy cell bank.

Methods

Expression of the markers CD90, CD105, CD44, and CD34 in SF-H, SM-H, SF-OA, SM-OA, SF-OCD and SM-OCD was verified by flow cytometry, and expression of cytokeratin, vimentin, PGP 9.5, PCNA, lysozyme, nanog, and Oct4 was verified by immunocytochemistry. MSCs were cultured and evaluated for their chondrogenic, osteogenic and adipogenic differentiation potential. Final quantification of extracellular matrix and mineralized matrix was determined using AxioVision software. A tumorigenicity test was conducted in Balb-C^nu/nu mice to verify the safety of the MSCs from these sources.

Results

Cultured cells from SF and SM exhibited fibroblastoid morphology and the ability to adhere to plastic. The time elapsed between primary culture and the third passage was approximately 73 days for SF-H, 89 days for SF-OCD, 60 days for SF-OA, 68 days for SM-H, 57 days for SM-OCD and 54 days for SM-OA. The doubling time for SF-OCD was higher than that for other cells at the first passage (P < 0.05). MSCs from synovial tissues showed positive expression of the markers CD90, CD44, lysozyme, PGP 9.5, PCNA and vimentin and were able to differentiate into chondrogenic (21 days) and osteogenic (21 days) lineages, and, although poorly, into adipogenic lineages (14 days). The areas staining positive for extracellular matrix in the SF-H and SM-H groups were larger than those in the SF-OA and SM-OA groups (P < 0.05). The positive mineralized matrix area in the SF-H group was larger than those in all the other groups (P < 0.05). The studied cells exhibited no tumorigenic effects.

Conclusions

SF and SM are viable sources of equine MSCs. All sources studied provide suitable MSCs for an allogeneic therapy cell bank; nevertheless, MSCs from healthy joints may be preferable for cell banking purposes because they exhibit better chondrogenic differentiation capacity.

Multiple Functions of MSCA-1/TNAP in Adult Mesenchymal Progenitor/Stromal Cells

Our knowledge about mesenchymal stem cells has considerably grown in the last years. Since the proof of concept of the existence of such cells in the 70s by Friedenstein et al., a growing mass of reports were conducted for a better definition of these cells and for the reevaluation from the term “mesenchymal stem cells” to the term “mesenchymal stromal cells (MSCs).” Being more than a semantic shift, concepts behind this new terminology reveal the complexity and the heterogeneity of the cells grouped in MSC family especially as these cells are present in nearly all adult tissues. Recently, mesenchymal stromal cell antigen-1 (MSCA-1)/tissue nonspecific alkaline phosphatase (TNAP) was described as a new cell surface marker of MSCs from different tissues. The alkaline phosphatase activity of this protein could be involved in wide range of MSC features described below from cell differentiation to immunomodulatory properties, as well as occurrence of pathologies. The present review aims to decipher and summarize the role of TNAP in progenitor cells from different tissues focusing preferentially on brain, bone marrow, and adipose tissue.

Differentiation ability of multipotent hematopoietic stem/progenitor cells detected by a porcine specific anti-CD117 monoclonal antibody

CD117 is a cytokine receptor expressed on the surface of hematopoietic stem cells with a likely role in cell survival, proliferation and differentiation. In order to study the differentiation activity of porcine CD117 hematopoietic cells in vitro and in vivo we prepared an anti-swine CD117 Mab (2A1) with high specificity for flow-cytometrical analysis. The 2A1 Mab did not recognize mouse or human mast cells suggesting that 2A1 is species-specific. Swine bone marrow (BM) CD117+ cells differentiated in vitro mainly into erythroid and monocyte lineages in the methylcellulose-based colony assay. When the swine BM CD117+ cells were transplanted in vivo into immunodeficient NOG (NOD/SCID/IL-2gc-null) mice, a significant amount of swine CD45+ leukocytes, including CD3 positive T cells, were developed in the mice. These results revealed that the swine BM CD117+ cells possess hematopoietic stem/progenitor activity and when monitored in immunodeficient mice or in vitro they can develop into lymphoid, erythroid, and myeloid cells efficiently with the new monoclonal antibody.

Ultrastructural study of cultured ovine bone marrow-derived mesenchymal stromal cells

Ovine bone marrow-derived mesenchymal stromal cells (oBM-MSCs) represent a good animal model for cell-based therapy and tissue engineering. Despite their use as a new therapeutic tool for several clinical applications, the morphological features of oBM-MSCs are yet unknown. Therefore, in this study the ultrastructural phenotype of these cells was analysed by transmission electron microscopy (TEM). The oBM-MSCs were isolated from the iliac crest and cultured until they reached near-confluence. After trypsinization, they were processed to investigate their ultrastructural features as well as specific surface marker proteins by flow cytometry and immunogold electron microscopy. Flow cytometry displayed that all oBM-MSCs lacked expression of CD31, CD34, CD45, HLA-DR whereas they expressed CD44, CD58, HLAI and a minor subset of the cell population (12%) exhibited CD90. TEM revealed the presence of two morphologically distinct cell types: cuboidal electron-lucent cells and spindle-shaped electron-dense cells, both expressing the CD90 antigen. Most of the electron-lucent cells showed glycogen aggregates, dilated cisternae of RER, moderately developed Golgi complex, and secretory activity. The electron-dense cell type was constituted by two different cell-populations: type A cells with numerous endosomes, dense bodies, rod-shaped mitochondria and filopodia; type B cells with elongated mitochondria, thin pseudopodia and cytoplasmic connectivity with electron-lucent cells. These morphological findings could provide a useful support to identify "in situ" the cellular components involved in the cell-therapy when cultured oBM-MSCs are injected.

Isolation and characterisation of mesenchymal stem/stromal cells in the ovine endometrium

Objective

Mesenchymal stem/stromal cells (MSC) were recently discovered in the human endometrium. These cells possess key stem cell properties and show promising results in small animal models when used for preclinical tissue engineering studies. A small number of surface markers have been identified that enrich for MSC from bone marrow and human endometrium, including the Sushi Domain-containing 2 (SUSD2; W5C5) and CD271 markers. In preparation for developing a large animal preclinical model for urological and gynecological tissue engineering applications we aimed to identify and characterise MSC in ovine endometrium and determine surface markers to enable their prospective isolation.

Materials and Methods

Ovine endometrium was obtained from hysterectomised ewes following progesterone synchronisation, dissociated into single cell suspensions and tested for MSC surface markers and key stem cell properties. Purified stromal cells were obtained by flow cytometry sorting with CD49f and CD45 to remove epithelial cells and leukocytes respectively, and MSC properties investigated.

Results

There was a small population CD271⁺ stromal cells (4.5 ± 2.3%) in the ovine endometrium. Double labelling with CD271 and CD49f showed that the sorted CD271⁺CD49f^- stromal cell population possessed significantly higher cloning efficiency, serial cloning capacity and a qualitative increased ability to differentiate into 4 mesodermal lineages (adipocytic, smooth muscle, chondrocytic and osteoblastic) than CD271^-CD49f^- cells. Immunolabelling studies identified an adventitial perivascular location for ovine endometrial CD271⁺ cells.

Conclusion

This is the first study to characterise MSC in the ovine endometrium and identify a surface marker profile identifying their location and enabling their prospective isolation. This knowledge will allow future preclinical studies with a large animal model that is well established for pelvic organ prolapse research.

In vitro and in vivo antiproliferative activity of metformin on stem-like cells isolated from spontaneous canine mammary carcinomas: translational implications for human tumors

Background

Cancer stem cells (CSCs) are considered the cell subpopulation responsible for breast cancer (BC) initiation, growth, and relapse. CSCs are identified as self-renewing and tumor-initiating cells, conferring resistance to chemo- and radio-therapy to several neoplasias. Nowadays, th (about 10mM)e pharmacological targeting of CSCs is considered an ineludible therapeutic goal. The antidiabetic drug metformin was reported to suppress in vitro and in vivo CSC survival in different tumors and, in particular, in BC preclinical models. However, few studies are available on primary CSC cultures derived from human postsurgical BC samples, likely because of the limited amount of tissue available after surgery. In this context, comparative oncology is acquiring a relevant role in cancer research, allowing the analysis of larger samples from spontaneous pet tumors that represent optimal models for human cancer.

Methods

Isolation of primary canine mammary carcinoma (CMC) cells and enrichment in stem-like cell was carried out from fresh tumor specimens by culturing cells in stem-permissive conditions. Phenotypic and functional characterization of CMC-derived stem cells was performed in vitro, by assessment of self-renewal, long-lasting proliferation, marker expression, and drug sensitivity, and in vivo, by tumorigenicity experiments. Corresponding cultures of differentiated CMC cells were used as internal reference. Metformin efficacy on CMC stem cell viability was analyzed both in vitro and in vivo.

Results

We identified a subpopulation of CMC cells showing human breast CSC features, including expression of specific markers (i.e. CD44, CXCR4), growth as mammospheres, and tumor-initiation in mice. These cells show resistance to doxorubicin but were highly sensitive to metformin in vitro. Finally, in vivo metformin administration significantly impaired CMC growth in NOD-SCID mice, associated with a significant depletion of CSCs.

Conclusions

Similarly to the human counterpart, CMCs contain stem-like subpopulations representing, in a comparative oncology context, a valuable translational model for human BC, and, in particular, to predict the efficacy of antitumor drugs. Moreover, metformin represents a potential CSC-selective drug for BC, as effective (neo-)adjuvant therapy to eradicate CSC in mammary carcinomas of humans and animals.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1235-8) contains supplementary material, which is available to authorized users.

Therapeutic mesenchymal stromal cells: where we are headed

With a range of therapeutic uses, from diabetes and Crohn's disease to wound repair, interest in the function, characterization, and expansion of mesenchymal stromal cells (MSCs) is growing rapidly. When considering the therapeutic use of MSCs, one must take into account a multitude of options including the ideal source of MSCs, the ideal donor, and the best means of expansion. Here we discuss different sources of MSCs, including cord blood, bone marrow, and adipose tissue, the option of using autologous and allogeneic donors, and finally we discuss GMP-applicable expansion protocols aimed at expanding MSCs for clinical use.

Phenotypical and functional characteristics of mesenchymal stem cells derived from equine umbilical cord blood

Mesenchymal stem cells (MSCs) offer promise as therapeutic aid in the repair of tendon and ligament injuries in race horses. Fetal adnexa is considered as an ideal source of MSCs due to many advantages, including non-invasive nature of isolation procedures and availability of large tissue mass for harvesting the cells. However, MSCs isolated from equine fetal adnexa have not been fully characterized due to lack of species-specific markers. Therefore, this study was carried out to isolate MSCs from equine umbilical cord blood (UCB) and characterize them using cross-reactive markers. The plastic-adherent cells could be isolated from 13 out of 20 (65 %) UCB samples. The UCB derived cells proliferated till passage 20 with average cell doubling time of 46.40 ± 2.86 h. These cells expressed mesenchymal surface markers but did not express haematopoietic/leucocytic markers by RT-PCR and immunocytochemistry. The phenotypic expression of CD29, CD44, CD73 and CD90 was shown by 96.36 ± 1.28, 93.40 ± 0.70, 73.23 ± 1.29 and 46.75 ± 3.95 % cells, respectively in flow cytometry, whereas, reactivity against the haematopoietic antigens CD34 and CD45 was observed only in 2.4 ± 0.20 and 0.1 ± 0.0 % of cells, respectively. Osteogenic and chondrogenic differentiation could be achieved using established methods, whereas the optimum adipogenic differentiation was achieved after supplementing media with 15 % rabbit serum and 20 ng/ml of recombinant human insulin. In this study, we optimized methodology for isolation, cultural characterization, differentiation and immunophenotyping of MSCs from equine UCB. Protocols and markers used in this study can be employed for unequivocal characterization of equine MSCs.

Mesenchymal stem-cell potential in cartilage repair: an update

Articular cartilage damage and subsequent degeneration are a frequent occurrence in synovial joints. Treatment of these lesions is a challenge because this tissue is incapable of quality repair and/or regeneration to its native state. Non-operative treatments endeavour to control symptoms and include anti-inflammatory medications, viscosupplementation, bracing, orthotics and activity modification. Classical surgical techniques for articular cartilage lesions are frequently insufficient in restoring normal anatomy and function and in many cases, it has not been possible to achieve the desired results. Consequently, researchers and clinicians are focusing on alternative methods for cartilage preservation and repair. Recently, cell-based therapy has become a key focus of tissue engineering research to achieve functional replacement of articular cartilage. The present manuscript is a brief review of stem cells and their potential in the treatment of early OA (i.e. articular cartilage pathology) and recent progress in the field.

Immunophenotype and gene expression profile of mesenchymal stem cells derived from canine adipose tissue and bone marrow

Veterinary adult stem cell therapy is an emerging area of basic and clinical research. Like their human counterparts, veterinary mesenchymal stem cells (MSCs) offer many potential therapeutic benefits. The characterization of canine-derived MSCs, however, is poorly defined compared to human MSCs. Furthermore, little consensus exists regarding the expression of canine MSC cell surface markers. To address this issue, this study investigated characteristics of cultured canine MSCs derived from both adipose tissue and bone marrow. The canine MSCs were obtained from donors of various breeds and ages. A panel of cell surface markers for canine MSCs was selected based on current human and canine literature and the availability of canine-reactive antibodies. Using flow cytometry, canine MSCs were defined to be CD90(+)CD44(+)MHC I(+)CD14(-)CD29(-)CD34(-)MHC II(-). Canine MSCs were further characterized using real-time RT-PCR as CD105(+)CD73(+)CD14(+)CD29(+)MHC II(+)CD45(-) at the mRNA level. Among these markers, canine MSCs differed from canine peripheral blood mononuclear cells (PBMCs) by the absence of CD45 expression at the mRNA level. A novel high-throughput canine-specific PCR array was developed and used to identify changes in the gene expression profiles of canine MSCs. Genes including PTPRC, TNF, β2M, TGFβ1, and PDGFRβ, were identified as unique to canine MSCs as compared to canine PBMCs. Our findings will facilitate characterization of canine MSCs for use in research and clinical trials. Moreover, the high-throughput PCR array is a novel tool for characterizing canine MSCs isolated from different tissues and potentially from different laboratories.

BMP12 induces tenogenic differentiation of adipose-derived stromal cells

Adipose-derived stromal cells (ASCs) are pluripotent cells that have the capacity to differentiate into tendon fibroblasts (TFs). They are abundant in adults, easy to access, and are therefore an ideal cell source for tendon tissue engineering. Despite this potential, the molecular cues necessary for tenogenic differentiation of ASCs are unknown. Unlike other bone morphogenetic proteins (BMPs), BMP12, BMP13, and BMP14 have been reported to be less osteo-chondrogenic and to induce tendon rather than bone formation in vivo. This study investigated the effects of BMP12 and BMP14 on ASC differentiation in vitro. In canine ASCs, BMP12 effectively increased the expression of the tendon markers scleraxis and tenomodulin at both mRNA and protein levels. Consistent with these results, BMP12 induced scleraxis promoter driven-GFP and tenomodulin protein expression in mouse ASCs. Although BMP12 also enhanced the expression of the cartilage matrix gene aggrecan in ASCs, the resulting levels remained considerably lower than those detected in tendon fibroblasts. In addition, BMP12 reduced expression of the bone marker osteocalcin, but not the osteogenic transcription factor runx-2. BMP14 exhibited similar, but marginally less potent and selective effects, compared to BMP12. BMPs are known to signal through the canonical Smad pathway and the non-canonical mitogen-activated protein kinase (MAPK) pathway. BMP12 triggered robust phosphorylation of Smad1/5/8 but not Smad2/3 or p38 MAPK in ASCs. The effect was likely conveyed by type I receptors ALK2/3/6, as phosphorylation of Smad1/5/8 was blocked by the ALK2/3/6 inhibitor LDN-193189 but not by the ALK4/5/7 inhibitor SB-505124. Moreover, ALK6 was found to be the most abundant type I receptor in ASCs, with mRNA expression 100 to 10,000 times that of any other type I receptor. Collectively, results support the conclusion that BMP12 induces tenogenic differentiation of ASCs via the Smad1/5/8 pathway.

Mesenchymal stromal cells from unconventional model organisms

Mesenchymal stromal cells (MSCs) are multipotent, plastic, adherent cells able to differentiate into osteoblasts, chondroblasts and adipocytes. MSCs can be isolated from many different body compartments of adult and fetal individuals. The most commonly studied MSCs are isolated from humans, mice and rats. However, studies are also being conducted with the use of MSCs that originate from different model organisms, such as cats, dogs, guinea pigs, ducks, chickens, buffalo, cattle, sheep, goats, horses, rabbits and pigs. MSCs derived from unconventional model organisms all present classic fibroblast-like morphology, the expression of MSC-associated cell surface markers such as CD44, CD73, CD90 and CD105 and the absence of CD34 and CD45. Moreover, these MSCs have the ability to differentiate into osteoblasts, chondroblasts and adipocytes. The MSCs isolated from unconventional model organisms are being studied for their potential to heal different tissue defects and injuries and for the development of scaffold compositions that improve the proliferation and differentiation of MSCs for tissue engineering.

CD271 as a marker for mesenchymal stem cells in bone marrow versus umbilical cord blood

CD271 has been applied to isolate mesenchymal stem cells (MSCs) from bone marrow and other tissues. Umbilical cord blood is a unique resource of stem cells and endothelial progenitor cells. Isolation of MSCs from umbilical cord blood, however, has been inefficient and inconsistent. This study was designed to examine the potential application of CD271 as a marker for the isolation of MSCs from umbilical cord blood. CD271+ cells were isolated from umbilical cord blood and bone marrow using CD271 antibody-conjugated microbeads, and characterized in osteogenic, chondrogenic and adipogenic differentiation. CD271+ cells from umbilical cord blood were slow to proliferate compared with those isolated from bone marrow. While CD271+ cells from bone marrow differentiated into osteogenic, chondrogenic and adipogenic lineages, there were no sound indications of differentiation by CD271+ cells from umbilical cord blood under the same differentiation conditions applied to the CD271+ cells from bone marrow. The study also found that bone marrow CD271+ cells remarkably upregulated the expression of chondrogenic genes under chondrogenic differentiation induction. When implanted into bone defects in mice, CD271+ cells from bone marrow regenerated significant bone, but the counterparts in umbilical cord blood formed little bone in the bone defects. In conclusion, CD271 is an efficient marker for MSC isolation from bone marrow but has failed to isolate MSCs from umbilical cord blood. CD271+ cells in bone marrow are particularly chondrogenic. The property of CD271+ cells is unique but varies from different tissues.

Human versus porcine mesenchymal stromal cells: phenotype, differentiation potential, immunomodulation and cardiac improvement after transplantation

Although mesenchymal stromal cells (MSCs) have been applied clinically to treat cardiac diseases, it is unclear how and to which extent transplanted MSCs exert their beneficial effects. To address these questions, pre-clinical MSC administrations are needed for which pigs appear to be the species of choice. This requires the use of porcine cells to prevent immune rejection. However, it is currently unknown to what extent porcine MSCs (pMSCs) resemble human MSCs (hMSCs). Aim of this study was to compare MSC from porcine bone marrow (BM) with human cells for phenotype, multi-lineage differentiation potential, immune-modulatory capacity and the effect on cardiac function after transplantation in a mouse model of myocardial infarction. Flow cytometric analysis revealed that pMSC expressed surface antigens also found on hMSC, including CD90, MSCA-1 (TNAP/W8B2 antigen), CD44, CD29 and SLA class I. Clonogenic outgrowth was significantly enriched following selection of CD271+ cells from BM of human and pig (129 ± 29 and 1961 ± 485 fold, respectively). hMSC and pMSC differentiated comparably into the adipogenic, osteogenic or chondrogenic lineages, although pMSC formed fat much faster than hMSC. Immuno-modulation, an important feature of hMSC, was clearly demonstrated for pMSC when co-cultured with porcine peripheral blood cells stimulated with PMA and pIL-2. Finally, pMSC transplantation after myocardial infarction attenuated adverse remodelling to a similar extent as hMSC when compared to control saline injection. These findings demonstrate that pMSCs have comparable characteristics and functionality with hMSCs, making reliable extrapolation of pre-clinical pMSC studies into a clinical setting very well possible.

Markers for characterization of bone marrow multipotential stromal cells

Given the observed efficacy of culture-expanded multipotential stromal cells, also termed mesenchymal stem cells (MSCs), in the treatment of graft-versus host and cardiac disease, it remains surprising that purity and potency characterization of manufactured cell batches remains rather basic. In this paper, we will initially discuss surface and molecular markers that were proposed to serve as the indicators of the MSC potency, in terms of their proliferative potential or the ability to differentiate into desired lineages. The second part of this paper will be dedicated to a critical discussion of surface markers of uncultured (i.e., native) bone marrow (BM) MSCs. Although no formal consensus has yet been reached on which markers may be best suited for prospective BM MSC isolation, markers that cross-react with MSCs of animal models (such as CD271 and W8-B2/MSCA-1) may have the strongest translational value. Whereas small animal models are needed to discover the in vivo function on these markers, large animal models are required for safety and efficacy testing of isolated MSCs, particularly in the field of bone and cartilage tissue engineering.