Isolation and characterisation of peripheral blood-derived feline mesenchymal stem cells

Stem Cell-Based Therapies for Glaucoma Treatment: A Review Bridging the Gap in Veterinary Patients

Retinal diseases are characterized by progressive damage to retinal cells, leading to irreversible vision loss. Among these, glaucoma stands out as a multifactorial neurodegenerative disease involving elevated intraocular pressure, retinal ganglion cell apoptosis, and optic nerve damage, ultimately resulting in blindness in both humans and dogs. Stem cell-based therapies have emerged as a promising therapeutic option for such conditions due to their regenerative and neuroprotective potential. These therapies, particularly those based on mesenchymal stem cells, offer the potential to repair and protect retinal tissues through the bioactive molecules (growth factors, cytokines, chemokines) secreted, their secretome. However, research in this field, especially on the use of umbilical cord mesenchymal stem cells' secretome, remains sparse. Most clinical trials focus on human glaucomatous patients, leaving a significant gap in veterinary patients' application, especially in dogs, with additional research being needed to determine its usefulness in canine glaucoma treatment. Future studies should aim to evaluate these therapies across both human and veterinary contexts, broadening treatment possibilities for glaucoma.

Bovine Peripheral Blood-Derived Mesenchymal Stem Cells (PB-MSCs) and Spermatogonial Stem Cells (SSCs) Display Contrasting Expression Patterns of Pluripotency and Germ Cell Markers under the Effect of Sertoli Cell Conditioned Medium

In vitro gamete derivation has been proposed as an interesting strategy for treatment of infertility, improvement of genetic traits, and conservation of endangered animals. Spermatogonial stem cells (SSCs) are primary candidates for in vitro gamete derivation; however, recently, mesenchymal stem cells (MSCs) have also been proposed as candidates for germ cell (GCs) differentiation mainly due to their transdifferentiating capacity. The objective of the present study was to compare the potential for GC differentiation of bovine peripheral blood-derived MSCs (PB-MSCs) and SSCs under the effect of conditioned medium (CM) derived from Sertoli cells (SCs/CM). Samples were collected every 7 days for 21 days and analyzed for pluripotent, GC, and MSC marker expression. The absence of OCT4 and the increased (p < 0.05) expression of NANOG seems to play a role in SSC differentiation, whereas the absence of NANOG and the increased expression (p < 0.05) of OCT4 may be required for PB-MSC differentiation into GCs. SSCs cultured with SCs/CM increased (p < 0.05) the expression of PIWIL2 and DAZL, while PB-MSCs cultured under the same condition only increased (p < 0.05) the expression of DAZL. Overall, the patterns of markers expression suggest that PB-MSCs and SSCs activate different signaling pathways after exposure to SCs/CM and during differentiation into GCs.

Influence of the Anatomical Site on Adipose Tissue-Derived Stromal Cells' Biological Profile and Osteogenic Potential in Companion Animals

Adipose tissue-derived stromal cells (ADSCs) have generated considerable interest in the field of veterinary medicine, particularly for their potential in therapeutic strategies focused on bone regeneration. These cells possess unique biological characteristics, including their regenerative capacity and their ability to produce bioactive molecules. However, it is crucial to recognize that the characteristics of ADSCs can vary depending on the animal species and the site from which they are derived, such as the subcutaneous and visceral regions (SCAT and VAT, respectively). Thus, the present work aimed to comprehensively review the different traits of ADSCs isolated from diverse anatomical sites in companion animals, i.e., dogs, cats, and horses, in terms of immunophenotype, morphology, proliferation, and osteogenic differentiation potential. The findings indicate that the immunophenotype, proliferation, and osteogenic potential of ADSCs differ according to tissue origin and species. Generally, the proliferation rate is higher in VAT-derived ADSCs in dogs and horses, whereas in cats, the proliferation rate appears to be similar in both cells isolated from SCAT and VAT regions. In terms of osteogenic differentiation potential, VAT-derived ADSCs demonstrate the highest capability in cats, whereas SCAT-derived ADSCs exhibit superior potential in horses. Interestingly, in dogs, VAT-derived cells appear to have greater potential than those isolated from SCAT. Within the VAT, ADSCs derived from the falciform ligament and omentum show increased osteogenic potential, compared to cells isolated from other anatomical locations. Consequently, considering these disparities, optimizing isolation protocols becomes pivotal, tailoring them to the specific target species and therapeutic aims, and judiciously selecting the anatomical site for ADSC isolation. This approach holds promise to enhance the efficacy of ADSCs-based bone regenerative therapies.

Feline umbilical cord mesenchymal stem cells: Isolation and in vitro characterization from distinct parts of the umbilical cord

Mesenchymal stromal/stem cells (MSCs) are a particular population of cells that play an essential role in the regeneration potential of the body. As a source of MSCs, the umbilical cord (UC) has significant advantages, such as a no-risk procedure of tissue retrieval after birth and the easiness of MSCs isolation. In the presented study, the cells derived from the feline whole umbilical cord (WUC) and two separate parts of the UC tissue, including Wharton's jelly (WJ) and umbilical cord vessels (UCV), were investigated to check whether they exhibit MSCs characteristics. The cells were isolated and characterized based on their morphology, pluripotency, differentiation potential, and phenotype. In our study MSCs were successfully isolated and cultured from all UC parts; after one week of culture, the cells had a typical spindle shape consistent with MSCs morphology. Cells showed the ability to differentiate into chondrocytes, osteoblasts and adipocytes cells. Two markers typical of MSCs (CD44, CD90) and three pluripotency markers (Oct4, SOX2 and Nanog) were expressed in all cells cultures; but no expression of (CD34, MCH II) was evidenced by flow cytometry and RT-PCR. In addition, WJ-MSCs showed the highest ability of proliferation, more significant pluripotency gene expressions, and greater differentiation potential than the cells isolated from WUC and UCV. Finally, we conclude in this study that cat MSCs derived from all the parts are valuable cells that can be efficiently used in various fields of feline regenerative medicine, but cells from WJ can offer the best clinical utility.

Retinoic acid induces the osteogenic differentiation of cat adipose tissue-derived stromal cells from distinct anatomical sites

Mesenchymal stromal cells-based regenerative orthopedic therapies have been used in cats as a promising and innovative therapeutic approach to enhance the repair of bone defects. Adipose tissue-derived stromal cells (ADSCs) can be obtained from two main sites-subcutaneous and visceral-with established differences regarding structure, composition, cell content, and functionality. However, in cats, to the best of the authors' knowledge, no studies have been conducted to compare the functional activity of the ADSCs isolated from the two sites, and the impact of these differences on the induced osteogenic potential. Additionally, retinoic acid has been recently regarded as a new osteogenic inducer within cells of distinct species, with undisclosed functionality on cat-derived cell populations. Thus, the present study aimed to evaluate the functional activity of ADSCs isolated from the subcutaneous and visceral adipose sites (SCAT and VAT, respectively) of the cat, as well as the effects of two osteogenic-inducing conditions-the classic dexamethasone, β-glycerophosphate and ascorbic acid-supplemented media (Dex + β + AAM), and Retinoic Acid-supplemented media (RAM). The adipose tissue of subcutaneous and visceral origin was isolated, characterized, and ADSCs were isolated and grown in the presence of the two osteogenic-inducing conditions, and characterized in terms of proliferation, metabolic activity, morphology, and osteogenic activity. Our results demonstrated a distinct biological profile of the two adipose tissue sites regarding cell size, vascularization, and morphology. Further, osteogenic-induced ADSCs from both sites presented an increased expression of alkaline phosphatase activity (ALP) and cytochemical staining, as compared with control. Overall, RAM induced higher levels of ALP activity than Dex + β + AAM, supporting an increased osteogenic activation. Additionally, VAT was the tissue with the best osteogenic potential, showing higher levels of ALP expression, particularly with RAM. In conclusion, different characteristics were found between the two adipose tissue sites-SCAT and VAT, which probably reflect the differences found in the functionality of isolated ADSCs from both tissues. Furthermore, for cat, VAT shows a greater osteogenic-inductive capacity than SCAT, particularly with RAM, which can be of therapeutic relevance for regenerative medicine applications.

Isolation and characterization of feline dental pulp stem cells

OBJECTIVES

The aim of this study was to isolate feline dental pulp stem cells (fDPSCs) and characterize their clonogenic and proliferative abilities, as well as their multipotency, immunophenotype and cytogenetic stability.

METHODS

Dental pulp was isolated by explant culture from two cats <1 year old at post mortem. Their clonogenicity was characterized using a colony-forming unit fibroblast assay, and their proliferative ability was quantified with a doubling time assay in passages 2, 4 and 6 (P2, P4 and P6, respectively). Multipotency was characterized with an in vitro trilineage differentiation assay in P2, and cells were immunophenotyped in P4 by flow cytometry. Chromosomic stability was evaluated by cytogenetic analysis in P2, P4 and P6.

RESULTS

The fDPSCs displayed spindle and epithelial-like morphologies. Isolated cells showed a marked clonogenic capacity and doubling time was maintained from P2 to P6. Trilineage differentiation was obtained in one sample, while the other showed osteogenic and chondrogenic differentiation. Immunophenotypic analysis showed fDPSCs were CD45-, CD90+ and CD44+. Structural and numerical cytogenetic aberrations were observed in P2-P4.

CONCLUSIONS AND RELEVANCE

In this study, fDPSCs from two cats were isolated by explant culture and immunophenotyped. Cells displayed clonogenic and proliferative ability, and multipotency in vitro, and signs of chromosomic instability were observed. Although a larger study is needed to confirm these results, this is the first report of fDPSC isolation and in vitro characterization.

Isolation and Characterization of Cat Olfactory Ecto-Mesenchymal Stem Cells

Simple Summary

Cat’s health is impacted by several diseases and lesions for which cell therapy could be an interesting treatment. Mesenchymal stem cells or adult stem cells are found in developed tissue. Olfactory mucosa contains stem cells called olfactory ecto-mesenchymal stem cells which have already been isolated from various animals as dogs and horses. The aim of this study was to evaluate the feasibility of collecting olfactory ecto-mesenchymal stem cells in cats. For that purpose, four cats were biopsied; the cells were collected and characterized. They show stemness features and differentiation capabilities as all the other mammals previously studied. Therefore, olfactory ecto-mesenchymal stem cells could be a promising tool for feline regenerative medicine.

Abstract

The olfactory mucosa contains olfactory ecto-mesenchymal stem cells (OE-MSCs) which show stemness features, multipotency capabilities, and have a therapeutic potential. The OE-MSCs have already been collected and isolated from various mammals. The aim of this study was to evaluate the feasibility of collecting, purifying and amplifying OE-MSCs from the cat nasal cavity. Four cats were included in the study. Biopsies of olfactory mucosa were performed on anesthetized animals. Then, the olfactory OE-MSCs were isolated, and their stemness features as well as their mesodermal differentiation capabilities were characterized. Olfactory mucosa biopsies were successfully performed in all subjects. From these biopsies, cellular populations were rapidly generated, presenting various stemness features, such as a fibroblast-like morphology, nestin and MAP2 expression, and sphere and colony formation. These cells could differentiate into neural and mesodermal lineages. This report shows for the first time that the isolation of OE-MSCs from cat olfactory mucosa is possible. These cells showed stemness features and multilineage differentiation capabilities, indicating they may be a promising tool for autologous grafts and feline regenerative medicine.

Viability, yield and expansion capability of feline MSCs obtained from subcutaneous and reproductive organ adipose depots

BACKGROUND

The source of multipotent stromal cells (MSC) can have a significant influence on the health and expansion capacity of the cells. As the applications for allogeneic MSCs in the treatment of feline diseases increase, the location of the initial donor tissue must be analyzed. To date, comparisons have only been made between feline MSCs collected from bone marrow or abdominal fat. This is the first report to compare cells obtained from different adipose depots in the cat with a focus on clinically relevant donor tissues. The tissue was collected from 34 healthy cats undergoing spaying (fat around the ovaries and uterine horn) or subcutaneous fat collected during surgical procedures.

RESULTS

The amount of starting material is essential to isolate sufficient MSCs. The total tissue yield from the subcutaneous fat was significantly greater than could be obtained from around the reproductive organs, leading to 3 times more MSCs per donor. However, the concentration of MSCs obtained from reproductive fat was higher than from subcutaneous fat. In addition, the viability of the MSCs from the reproductive fat was significantly higher than the subcutaneous fat. Since most spaying occurs in young cats (under 18 months) reproductive fat was collected from adult cats during spaying, illustrating that age did not alter the yield or viability of the MSCs. When sufficient tissue was collected, it was digested either mechanically or enzymatically. Mechanical digestion further decreased the viability and yield of MSCs from subcutaneous fat compared to enzymatic digestion. Biomarkers of stem cell characterization, expansion capacity and function were detected using qPCR. CD70, CD90 and CD105 were all expressed in high levels in the 3 groups. However, the reproductive fat had higher levels of CD73 with the mechanically digested subcutaneous fat having the least. Gata6 was detected in all samples while Sox2 and Sox17 were also detected with higher quantities found in the enzymatically digested subcutaneous fat. Negative control genes of Gata4 and Pdx1 showed no detection prior to 50 cycles. During the first three passages, age of the donor, location of the donor tissue, or digestion protocol had no effect on cell culture doubling times or cell viability.

CONCLUSIONS

While MSCs from reproductive fat had superior cells/tissue weight and initial viability, there were still dramatically fewer cells obtained compared to subcutaneous fat due to the limited amount of tissue surrounding the reproductive organs. Further, in P1-P3 cultures there were no differences noted in doubling time or cell viability between tissue obtained from reproductive or subcutaneous fat depots.

Isolation and Characterization of Feline Wharton's Jelly-Derived Mesenchymal Stem Cells

Wharton’s jelly is a well-known mesenchymal stem cell source in many species, including humans. However, there have been no reports confirming the presence of mesenchymal stem cells in Wharton’s jelly in cats. The purpose of this study was to isolate mesenchymal stem cells (MSCs) from the Wharton’s jelly of cats and to characterize stem cells. In this study, feline Wharton’s jelly-derived mesenchymal stem cells (fWJ-MSCs) were isolated and successfully cultured. fWJ-MSCs were maintained and the proliferative potential was measured by cumulative population doubling level (CPDL) test, scratch test, and colony forming unit (CFU) test. Stem cell marker, karyotyping and immunophenotyping analysis by flow cytometry showed that fWJ-MSCs possessed characteristic mesenchymal stem cell markers. To confirm the differentiation potential, we performed osteogenic, adipogenic and chondrogenic induction under each differentiation condition. fWJ-MSCs has the ability to differentiate into multiple lineages, including osteogenic, adipogenic and chondrogenic differentiation. This study shows that Wharton’s jelly of cat can be a good source of mesenchymal stem cells. In addition, fWJ-MSCs may be useful for stem cell-based therapeutic applications in feline medicine.

Proteomic Analysis of the Secretome and Exosomes of Feline Adipose-Derived Mesenchymal Stem Cells

Simple Summary

The enormous advances in stem cell research have generated high expectations in the development of new therapies to repair or regenerate damaged tissues. For this reason, laboratory studies of stem cells enable scientists to learn about cells’ essential properties. Specifically, in recent years, therapies based on mesenchymal stem cells have become an interesting alternative for the treatment of different complex pathologies in veterinary medicine. Mesenchymal stem cells secrete a wide variety of therapeutic elements such as bioactive molecules and extracellular vesicles (e.g., exosomes). Thus, it is essential to characterize them before future use as biotechnological products. Therefore, the objective of this study was to determine and compare their protein profile to understand better the mechanisms of action of these components and facilitate their possible use in future therapies. The data demonstrate the existence of different proteins responsible for the biological effects of cells. In addition, these approaches and techniques can contribute to the better prediction of clinical outcomes of mesenchymal stem cell treatment.

Abstract

Mesenchymal stem cells (MSCs) have been shown to have therapeutic efficacy in different complex pathologies in feline species. This effect is attributed to the secretion of a wide variety of bioactive molecules and extracellular vesicles, such as exosomes, with significant paracrine activity, encompassed under the concept of the secretome. However, at present, the exosomes from feline MSCs have not yet been studied in detail. The objective of this study is to analyze and compare the protein profiles of the secretome as a whole and its exosomal fraction from feline adipose-derived MSCs (fAd-MSCs). For this, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Protein–Protein Interaction Networks Functional Enrichment Analysis (STRING) were utilized. A total of 239 proteins were identified in the secretome, and 228 proteins specific to exosomes were identified, with a total of 133 common proteins. The proteins identified in the secretome were located in the extracellular regions and in the cytoplasm, while the exosomal proteins were located mainly in the membrane, cytoplasm and cytosol. Regarding function, in the secretome, proteins involved in different metabolic pathways, in pathways related to the immune system and the endocrine system and in the processing of proteins in the endoplasmic reticulum predominated. In contrast, proteins specific to exosomes were predominantly associated with endocytosis, cell junctions, platelet activation and other cell signaling pathways. The possible future use of the secretome, or some of its components, such as exosomes, would provide a non-cell-based therapeutic strategy for the treatment of different diseases that would avoid the drawbacks of cell therapy.

Comparison of Canine and Feline Adipose-Derived Mesenchymal Stem Cells/Medicinal Signaling Cells With Regard to Cell Surface Marker Expression, Viability, Proliferation, and Differentiation Potential

Remarkable immunomodulatory abilities of mesenchymal stem cells, also called multipotent mesenchymal stromal cells or medicinal signaling cells (MSCs), have entailed significant advances in veterinary regenerative medicine in recent years. Despite positive outcomes from MSC therapies in various diseases in dogs and cats, differences in MSC characteristics between small animal veterinary patients are not well-known. We performed a comparative study of cells' surface marker expression, viability, proliferation, and differentiation capacity of adipose-derived MSCs (ADMSCs) from dogs and domestic cats. The same growth media and methods were used to isolate, characterize, and culture canine and feline ADMSCs. Adipose tissue was collected from 11 dogs and 8 cats of both sexes. The expression of surface markers CD44, CD90, and CD34 was detected by flow cytometry. Viability at passage 3 was measured with the hemocytometer and compared to the viability measured by flow cytometry after 1 day of handling. The proliferation potential of MSCs was measured by calculating cell doubling and cell doubling time from second to eighth passage. Differentiation potential was determined at early and late passages by inducing cells toward adipogenic, osteogenic, and chondrogenic differentiation using commercial media. Our study shows that the percentage of CD44⁺CD90⁺ and CD34^−/− cells is higher in cells from dogs than in cells from cats. The viability of cells measured by two different methods at passage 3 differed between the species, and finally, canine ADMSCs possess greater proliferation and differentiation potential in comparison to the feline ADMSCs.

Optimizing the recovery of peripheral blood mononuclear cells trapped in leukoreduction filters - A comparison study

Introduction

The isolation of captured peripheral blood mononuclear cells (PBMNCs) from leukoreduction filters (LRFs) can be of great importance in terms of bringing the lost cells back into use.

Objective

The aim of this study was to evaluate various methods based on their potential to recover the peripheral blood cells from LRFs with a focus on mononuclear cells (MNCs).

Method

For cell isolation from LRFs, three distinct methods (back-flushing, direct and vacuum pump) were compared through the calculation of the yield of isolated MNCs. The viability of extracted cells was determined by the flow cytometry technique. Moreover, the recovered MNCs were characterized regarding the presence of blood stem cell purification. The cell culture, microscopic observation, and immunophenotyping were employed to characterize the blood stem cells (hematopoietic, mesenchymal and progenitor endothelial stem cells).

Results

The yield of isolation obtained in the back-flushing, direct and vacuum pump methods were 17.7 ± 1.28, 17.3 ± 0.96 and 21.2 ± 0.90 percent, respectively. Although the highest potential for total blood cell recovery belonged to the vacuum pump method, the lowest cell viability (85.73 ± 4.84%) was observed in this method. However, the isolation process of the back-flushing and direct methods had less effect on cell viability. The characterization of the isolated MNCs displayed that the dominant positive phenotype was for CD34/CD45, indicating hematopoietic stem cells. In addition, the endothelial stem/progenitor cells were significantly detected as CD31/CD133 positive cells.

Conclusion

According to our results and considering the safety and efficiency potential of each of the applied methods, the back-flushing in comparison with the other methods can be considered a suitable procedure for MNC isolation from LRFs.

Bovine peripheral blood MSCs chemotax towards inflammation and embryo implantation stimuli

Mesenchymal stem cells (MSCs) have a great potential in regenerative medicine because of their multipotential and immunoregulatory capacities, while in early pregnancy they could participate in the immunotolerance of the mother towards the embryo. Peripheral blood constitutes an accessible source of MSCs. We successfully isolated peripheral blood MSC (pbMSCs) lines, with or without previous bone marrow mobilization. All pbMSCs lines obtained in both conditions presented classical MSC markers and properties, alkaline phosphatase activity and multipotent capacity to differentiate among adipogenic, osteogenic or chondrogenic lineages, and suppressed the proliferation of T cells. pbMSCs showed migratory capacity without cytokine stimulation while increasing their migration rate in the presence of inflammatory or embryo implantation stimuli. Interestingly, in contrast to MSCs derived from endometrial tissue, three pbMSCs lines also showed increased migration towards the IFN-τ implantation cytokine. Moreover, the secretome produced by an early implantation stage embryonic trophectoderm cell line showed a chemoattractant effect in pbMSCs. Our results suggest that circulating MSCs are present in the peripheral blood under healthy conditions. The fact that both the inflammation and implantation signals induced pbMSCs chemotaxis highlights MSC heterogeneity and suggests that their migratory capacity may differ according to their tissue of origin and would suggest the possible active recruitment of MSCs from bone marrow during pregnancy to repress the immune response to prevent the embryo rejection by the maternal organism.

Safety and immunomodulatory properties of equine peripheral blood-derived mesenchymal stem cells in healthy cats

OBJECTIVE

Due to the immunomodulatory properties of mesenchymal stem cells (MSCs) through stimulation of endogenous immune cells by paracrine signals and cell contact, they have been proposed as alternative treatment option for many inflammatory and immune-mediated diseases in veterinary medicine. However, the long-term cultivation possibilities of feline MSCs are currently compromised due to a restricted proliferation capacity. Therefore, the xenogeneic use of equine peripheral blood-derived MSCs (ePB-MSCs) would present an interesting alternative thanks to their superior cultivation properties. To the authors' knowledge, there are currently no safety reports concerning the xenogeneic use of ePB-MSCs in cats. Therefore, the overall goal of this preliminary study was to investigate if ePB-MSCs can safely be administered in healthy cats and by extension evaluating their immunogenic and immunomodulatory properties.

METHODS

Ten healthy cats were intravenously (i.v.) injected with 3 × 10⁵ ePB-MSCs at three time points (T₀, T₁, T₂). All cats were daily inspected by the caretaker and underwent a physical examination with hematological and biochemical analysis at day 0 (T₀), week 2 (T₁), week 4 (T₂) and week 6 (T₃) by a veterinarian. Furthermore, a modified mixed lymphocyte reaction (MLR) was performed at T₀ and T₃ for each cat in order to evaluate immunogenic and immunomodulatory properties of the ePB-MSCs RESULTS: No adverse clinical effects could be detected following repeated i.v. administration of ePB-MSCs in all cats. Significant lower protein (T₁: P-value = 0.002; T₂: P-value > 0.001; T₃: P-value = 0.004) and albumin levels (T₁: P-value = 0.003; T₂: P-value = 0.001) were seen after repeated administration of ePB-MSCs, compared to T₀. However, all biochemical and hematological parameters stayed within clinical acceptance level. In addition, the repeated injections did not induce a cellular immune response before and after repeated ePB-MSCs administration. Furthermore, convincing immunomodulatory properties of ePB-MSCs on feline peripheral blood mononuclear cells were confirmed in the MLR-assay CONCLUSION: This preliminary study demonstrates that ePB-MSCs can safely be administered in healthy cats and provide a promising alternative for the treatment of various inflammatory diseases in cats.

Stem Cells in Veterinary Medicine-Current State and Treatment Options

Regenerative medicine is a branch of medicine that develops methods to grow, repair, or replace damaged or diseased cells, organs or tissues. It has gained significant momentum in recent years. Stem cells are undifferentiated cells with the capability to self—renew and differentiate into tissue cells with specialized functions. Stem cell therapies are therefore used to overcome the body's inability to regenerate damaged tissues and metabolic processes after acute or chronic insult. The concept of stem cell therapy was first introduced in 1991 by Caplan, who proposed that massive differentiation of cells into the desired tissue could be achieved by isolation, cultivation, and expansion of stem cells in in vitro conditions. Among different stem cell types, mesenchymal stem cells (MSC) currently seem to be the most suitable for therapeutic purposes, based on their simple isolation and culturing techniques, and lack of ethical issues regarding their usage. Because of their remarkable immunomodulatory abilities, MSCs are increasingly gaining recognition in veterinary medicine. Developments are primarily driven by the limitations of current treatment options for various medical problems in different animal species. MSCs represent a possible therapeutic option for many animal diseases, such as orthopedic, orodental and digestive tract diseases, liver, renal, cardiac, respiratory, neuromuscular, dermal, olfactory, and reproductive system diseases. Although we are progressively gaining an understanding of MSC behavior and their mechanisms of action, some of the issues considering their use for therapy are yet to be resolved. The aim of this review is first to summarize the current knowledge and stress out major issues in stem cell based therapies in veterinary medicine and, secondly, to present results of clinical usage of stem cells in veterinary patients.

Characterization of mesenchymal stem cells derived from adipose tissue of a cougar (Puma concolor)

Adipose derived mesenchymal stem cells (AMSCs) have been isolated from domestic and wild cats. For wild cats, the isolation of AMSCs has been reported in the black-footed cats (Felis nigripes) and guigna (Leopardus guigna). Stromal vascular fraction (SVF) isolated from cougar adipose tissue have been used to restore elbow functionality in the cougar (Puma concolor) but multipotent characteristics of these cells have not been described. The present study describes for the first time the isolation and characterization of mesenchymal stem cells derived from adipose tissue of cougar. AMSCs and fibroblasts from six months female cougar were isolated and cultured in DMEM/F12, supplemented with FBS 10% + 1% Antibiotic/Antifungal + 2.4 mM L-Glutamine + 2.4 mM pyruvate up to passage 5. Expression of pluripotent and surface marker genes was evaluated at mRNA level. Mesodermal differentiation (adipogenic, osteogenic and chondrogenic) was described. AMSCs expressed mRNA of pluripotent genes Oct4, Nanog, Sox2 and Klf4 and surface markers Cd44, Cd90, Cd105 and MHCII. Fibroblasts showed similar mRNA expression with the exception of Sox2. AMSCs obtained from cougar exhibit multipotency features similar to domestic cats MSC, nevertheless, other analyses are required. AMSCs from cougar could be a source of interest for treatment of individuals that remain in captivity or arrive to wildlife rehabilitation centers.

Iberian pig mesenchymal stem/stromal cells from dermal skin, abdominal and subcutaneous adipose tissues, and peripheral blood: in vitro characterization and migratory properties in inflammation

Background

Recently, the capacity of mesenchymal stem/stromal cells (MSCs) to migrate into damaged tissues has been reported. For MSCs to be a promising tool for tissue engineering and cell and gene therapy, it is essential to know their migration ability according to their tissue of origin. However, little is known about the molecular mechanisms regulating porcine MSC chemotaxis. The aim of this study was to examine the migratory properties in an inflammatory environment of porcine MSC lines from different tissue origins: subcutaneous adipose tissue (SCA-MSCs), abdominal adipose tissue (AA-MSCs), dermal skin tissue (DS-MSCs) and peripheral blood (PB-MSCs).

Methods

SCA-MSCs, AA-MSCs, DS-MSCs and PB-MSCs were isolated and analyzed in terms of morphological features, alkaline phosphatase activity, expression of cell surface and intracellular markers of pluripotency, proliferation, in vitro chondrogenic, osteogenic and adipogenic differentiation capacities, as well as their ability to migrate in response to inflammatory cytokines.

Results

SCA-MSCs, AA-MSCs, DS-MSCs and PB-MSCs were isolated and showed plastic adhesion with a fibroblast-like morphology. All MSC lines were positive for CD44, CD105, CD90 and vimentin, characteristic markers of MSCs. The cytokeratin marker was also detected in DS-MSCs. No expression of MHCII or CD34 was detected in any of the four types of MSC. In terms of pluripotency features, all MSC lines expressed POU5F1 and showed alkaline phosphatase activity. SCA-MSCs had a higher growth rate compared to the rest of the cell lines, while the AA-MSC cell line had a longer population doubling time. All MSC lines cultured under adipogenic, chondrogenic and osteogenic conditions showed differentiation capacity to the previously mentioned mesodermal lineages. All MSC lines showed migration ability in an agarose drop assay. DS-MSCs migrated greater distances than the rest of the cell lines both in nonstimulated conditions and in the presence of the inflammatory cytokines TNF-α and IL-1β. SCA-MSCs and DS-MSCs increased their migration capacity in the presence of IL-1β as compared to PBS control.

Conclusions

This study describes the isolation and characterization of porcine cell lines from different tissue origin, with clear MSC properties. We show for the first time a comparative study of the migration capacity induced by inflammatory mediators of porcine MSCs of different tissue origin.

Mammalian MSC from selected species: Features and applications

Mesenchymal stromal/stem cells (MSC) are promising candidates for cellular therapy of different diseases in humans and in animals. Following the guidelines of the International Society for Cell Therapy, human MSC may be identified by expression of a specific panel of cell surface markers (CD105+, CD73+, CD90+, CD34-, CD14-, or CD11b-, CD79- or CD19-, HLA-DR-). In addition, multiple differentiation potential into at least the osteogenic, adipogenic, and chondrogenic lineage is a main criterion for MSC definition. Human MSC and MSC of a variety of mammals isolated from different tissues meet these criteria. In addition to the abovementioned, they express many more cell surface markers. Yet, these are not uniquely expressed by MSC. The gross phenotypic appearance like marker expression and differentiation potential is similar albeit not identical for MSC from different tissues and species. Similarly, MSC may feature different biological characteristics depending on the tissue source and the isolation and culture procedures. Their versatile biological qualities comprising immunomodulatory, anti-inflammatory, and proregenerative capacities rely largely on the migratory and secretory capabilities of MSC. They are attracted to sites of tissue lesion and secrete factors to promote self-repair of the injured tissue. This is a big perspective for clinical MSC applications in both veterinary and human medicine. Phase I/II clinical trials have been initiated to assess safety and feasibility of MSC therapies in acute and chronic disease settings. Yet, since the mode of MSC action in a specific disease environment is still unknown at large, it is mandatory to unravel the response of MSC from a given source onto a specific disease environment in suitable animal models prior to clinical applications. © 2017 International Society for Advancement of Cytometry.

Mobilization, Isolation and Characterization of Stem Cells from Peripheral Blood: a Systematic Review

Objectives

The purpose of this article is to systematically review the methods of mobilization, isolation and characterization of stem cells from peripheral blood and to discuss their potential therapeutic applications for bone tissue regeneration.

Material and Methods

An electronic literature search was performed through MEDLINE (PubMed) electronic database. The search was restricted to English language articles published during the last 10 years, from January 2006 to November 2016.

Results

In total, 37 literature sources were reviewed, and 11 of the most relevant articles that are suitable to the criteria were selected. Articles were analysed with data on animals and humans for mobilization, isolation and characterization of stem cells from peripheral blood. From the examination of selected articles, the mobilization materials, side effects, alternatives and factors affecting the extracted amount of mesenchymal stem cells (MSC) from mobilized peripheral blood of healthy individuals, as well as characterization of mobilized MSC were reviewed in this article.

Conclusions

Bone tissue engineering is a potential alternative strategy in bone regeneration and bone defect repair, however, insufficiency data display in the literature on potential therapeutic applications of peripheral blood stem cells for bone tissue regeneration.