Stem Cells, Regenerative Medicine, and Animal Models of Disease

Sodium selenite preserves rBM-MSCs' stemness, differentiation potential, and immunophenotype and protects them against oxidative stress via activation of the Nrf2 signaling pathway

BACKGROUND

The physiological level of reactive oxygen species (ROS) is necessary for many cellular functions. However, during the in-vitro manipulations, cells face a high level of ROS, leading to reduced cell quality. Preventing this abnormal ROS level is a challenging task. Hence, here we evaluated the effect of sodium selenite supplementation on the antioxidant potential, stemness capacity, and differentiation of rat-derived Bone Marrow MSCs (rBM-MSCs) and planned to check our hypothesis on the molecular pathways and networks linked to sodium selenite's antioxidant properties.

METHODS

MTT assay was used to assess the rBM-MSCs cells' viability following sodium selenite supplementation (concentrations of: 0.001, 0.01, 0.1, 1, 10 µM). The expression level of OCT-4, NANOG, and SIRT1 was explored using qPCR. The adipocyte differentiation capacity of MSCs was checked after Sodium Selenite treatment. The DCFH-DA assay was used to determine intracellular ROS levels. Sodium selenite-related expression of HIF-1α, GPX, SOD, TrxR, p-AKT, Nrf2, and p38 markers was determined using western blot. Significant findings were investigated by the String tool to picture the probable molecular network.

RESULTS

Media supplemented with 0.1 µM sodium selenite helped to preserve rBM-MSCs multipotency and keep their surface markers presentation; this also reduced the ROS level and improved the rBM-MSCs' antioxidant and stemness capacity. We observed enhanced viability and reduced senescence for rBM-MSCs. Moreover, sodium selenite helped in rBM-MSCs cytoprotection by regulating the expression of HIF-1 of AKT, Nrf2, SOD, GPX, and TrxR markers.

CONCLUSIONS

We showed that sodium selenite could help protect MSCs during in-vitro manipulations, probably via the Nrf2 pathway.

Regenerative Medicine Perspectives in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common gynecologic endocrine disorder in women between the ages of 15 and 40, with uncertain etiology. It is mostly presented with hyperandrogenism and insulin resistance along with a variety of comorbidities that significantly reduce a patient's quality of life. Many disturbed metabolic pathways are correlated with PCOS. Moreover, it is evident that there is a strong genetic factor for PCOS. Indeed, several altered gene expressions have been found in PCOS subjects, but the exact genetic origins are still unclear. The major treatment options such as pharmacological treatments are to improve the symptoms. In addition, surgical procedures (Bariatric surgery and assisted reproductive technologies) can be used to treat some of the patient's complications and reduce their severity. Generally, using pharmacological agents for a long period of time can increase the risk of adverse effects. Moreover, surgical options may have high-risk consequences. Herein, there is an undeniable need for a different multidisciplinary approach to PCOS. Regenerative medicine with the help of stem cells can develop a worthy alternative approach for the treatment of PCOS. Furthermore, animal models can provide valuable knowledge of genetic alterations and metabolic pathway disturbances in PCOS. They can also be used for testing novel treatments in pre-clinical stages. Therein, the current knowledge of PCOS and investigation about the potential role of regenerative medicine in developing new and more efficient treatments for PCOS are summarized here.

Subpopulations of miniature pig mesenchymal stromal cells with different differentiation potentials differ in the expression of octamer-binding transcription factor 4 and sex determining region Y-box 2

Objective

Human mesenchymal stromal cells (MSCs) exhibit variable differentiation potential and can be divided accordingly into distinct subpopulations whose ratios vary with donor age. However, it is unknown whether the same is true in pigs. This study investigated MSC subpopulations in miniature pig and compared their characteristics in young (2 to 3 months) and adult (27 to 35 months) pigs.

Methods

Osteogenic, chondrogenic, and adipogenic capacity of isolated MSCs was evaluated by von Kossa, Alcian blue, and oil red O staining, respectively. Cell surface antigen expression was determined by flow cytometry. Proliferative capacity was assessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Expression of marker genes was detected by quantitative real-time polymerase chain reaction.

Results

Porcine MSCs comprised cells with trilineage and bilineage differentiation potential (tMSCs and bMSCs, respectively) and non-differentiating stromal cells (NDSCs). The tMSC and bMSC fractions were smaller in adult than in young pigs (63.0% vs 71.2% and 11.6% vs 24.0%, respectively, p<0.05); NDSCs showed the opposite trend (25.4% vs 4.8%; p<0.05). Subpopulations showed no differences in morphology, cell surface antigen expression, or proliferative capacity, but octamer-binding transcription factor 4 (OCT4) expression was higher in tMSCs than in bMSCs and NDSCs (p<0.05), whereas sex determining region Y-box 2 (SOX2) expression was higher in tMSCs and bMSCs than in NDSCs (p<0.05). Aging had no effect on these trends.

Conclusion

Porcine MSCs comprise distinct subpopulations that differ in their differentiation potential and OCT4 and SOX2 expression. Aging does not affect the characteristics of each subpopulation but alters their ratios.

Potential Clinical Applications of Stem Cells in Regenerative Medicine

The field of regenerative medicine is looking for a pluripotent/multipotent stem cell able to differentiate across germ layers and be safely employed in therapy. Unfortunately, with the exception of hematopoietic stem/progenitor cells (HSPCs) for hematological applications, the current clinical results with stem cells are somewhat disappointing. The potential clinical applications of the more primitive embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have so far been discouraging, as both have exhibited several problems, including genomic instability, a risk of teratoma formation, and the possibility of rejection. Therefore, the only safe stem cells that have so far been employed in regenerative medicine are monopotent stem cells, such as the abovementioned HSPCs or mesenchymal stem cells (MSCs) isolated from postnatal tissues. However, their monopotency, and therefore limited differentiation potential, is a barrier to their broader application in the clinic. Interestingly, results have accumulated indicating that adult tissues contain rare, early-development stem cells known as very small embryonic-like stem cells (VSELs), which can differentiate into cells from more than one germ layer. This chapter addresses different sources of stem cells for potential clinical application and their advantages and problems to be solved.

Effect of granulocyte colony-stimulating factor administration on renal regeneration after experimentally induced acute kidney injury in dogs

OBJECTIVE

To evaluate the effects of granulocyte colony-stimulating factor (GCSF) administration in dogs with experimentally induced acute kidney injury.

ANIMALS

6 healthy dogs.

PROCEDURES

After induction of kidney injury (day 0) with cisplatin (5 mg/kg, IV), the dogs were randomly assigned into 2 groups (n = 3 dogs/group). Then dogs immediately received GCSF (10 μg/kg) or 1 mL of saline (0.9% NaCl) solution (control group) SC; this treatment was repeated once daily for 4 additional days (days 1 through 4). A once-daily CBC (day 0 to 4), serum biochemical analysis (day 0 to 3), and urinalysis (day 0 to 3) were performed for each dog; samples were collected before administration of cisplatin (day 0) and before treatment with GCSF or saline solution (days 1 through 4). After sample collection and treatment on day 4, all dogs were euthanized; kidney tissue samples underwent histologic evaluation, immunohistochemical analyses, and cytokine profiling via reverse transcriptase PCR assay.

RESULTS

In the GCSF-treated group, the histologic evaluation and immunohistochemical analyses of kidney tissue revealed less fibrotic change and greater proliferation of renal tubular epithelial cells, compared with findings in the control group. The mRNA profiles of kidney tissue from the GCSF-treated group indicated lower expression of tumor necrosis factor-α and tumor growth factor-β, compared with findings in the control group; however, concentrations of factors related to renal regeneration were not greater in the GCSF-treated group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that GCSF treatment can impede renal fibrosis and increase proliferation of renal tubules after experimentally induced acute kidney injury in dogs.

Low dose Hsp90 inhibitor 17AAG protects neural progenitor cells from ischemia induced death

Stress adaptation effect provides cell protection against ischemia induced apoptosis. Whether this mechanism prevents other types of cell death in stroke is not well studied. This is an important question for regenerative medicine to treat stroke since other types of cell death such as necrosis are also prominent in the stroke brain apart from apoptosis. We report here that treatment with 17-N-Allylamino-17-demethoxygeldanamycin (17AAG), an Hsp90 inhibitor, protected neural progenitor cells (NPCs) against oxygen glucose deprivation (OGD) induced cell death in a dose dependent fashion. Cell death assays indicated that 17AAG not only ameliorated apoptosis, but also necrosis mediated by OGD. This NPC protection was confirmed by exposing cells to oxidative stress, a major stress signal prevalent in the stroke brain. Mechanistic studies demonstrated that 17AAG activated PI3K/Akt and MAPK cell protective pathways. More interestingly, these two pathways were activated in vivo by 17AAG and 17AAG treatment reduced infarct volume in a middle cerebral artery occlusion (MCAO) stroke model. These data suggest that 17AAG protects cells against major cell death pathways and thus might be used as a pharmacological conditioning agent for regenerative medicine for stroke.

Isolation and morphological characterisation of ovine adipose-derived mesenchymal stem cells in culture

BACKGROUND AND OBJECTIVES

AD-MSCs (adipose-derived mesenchymal stem cells), as an easy obtainable population of multipotent cells, have been successfully applied in many diseases in animals. Having very similar properties and morphology to these collected from bone marrow, are very attractive object for regenerative medicine.

CONCLUSIONS

Ovine subcutaneous fat from many regions of the body is rich source of stem cells, which could be used in locomotive system disorders experimental therapy on sheep models.

Ex vivo reconstitution of arterial endothelium by embryonic stem cell-derived endothelial progenitor cells in baboons

There is an increasing need for an animal model that can be used to translate basic research into clinical therapy. We documented the differentiation and functional competence of embryonic stem cell (ESC)-derived endothelial cells in baboons. Baboon angioblasts were sequentially differentiated from embryoid body cultures for 9 days in an angioblast differentiation medium with varying concentrations of BMP-4, FLT-3 ligand, stem cell factor, thrombopoietin, basic fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), and knockout serum replacement. Real-time polymerase chain reaction results showed that ESC-derived angioblasts downregulated NANOG and OCT3/4, upregulated T-brachyury and GATA2, and moderately expressed CD34; they did not express CD144, TEK, or VWF, and varied in levels of CD31 expression. Several populations of putative angioblasts appeared 3 days and 9 days after differentiation, as identified by flow cytometry. Angioblasts at this stage exhibited dual paths of differentiation toward hematopoietic and vascular fates. To examine whether derived angioblasts could reconstitute the endothelium, we built an ex vivo culture system and seeded fluorescently labeled angioblast cultures onto a denuded segment of the femoral artery. We found that the seeded cells were able to grow into the endothelium on the interior surface of denuded artery segments within 5 days after seeding. After 14 days of ex vivo culture, the transplanted cells expressed CD31, an endothelial marker. The control arteries, seeded with vehicle only, did not harbor cells with endothelial markers. We conclude that ESC-derived angioblasts are promising therapeutic agents for repairing damaged vasculature, and that the baboon model will be vital for optimizing therapies for human clinical studies.

Reducing the number of laboratory animals used in tissue engineering research by restricting the variety of animal models. Articular cartilage tissue engineering as a case study

The use of laboratory animals in tissue engineering research is an important underexposed ethical issue. Several ethical questions may be raised about this use of animals. This article focuses on the possibilities of reducing the number of animals used. Given that there is considerable debate about the adequacy of the current animal models in tissue engineering research, we investigate whether it is possible to reduce the number of laboratory animals by selecting and using only those models that have greatest predictive value for future clinical application of the tissue engineered product. The field of articular cartilage tissue engineering is used as a case study. Based on a study of the scientific literature and interviews with leading experts in the field, an overview is provided of the animal models used and the advantages and disadvantages of each model, particularly in terms of extrapolation to the human situation. Starting from this overview, it is shown that, by skipping the small models and using only one large preclinical model, it is indeed possible to restrict the number of animal models, thereby reducing the number of laboratory animals used. Moreover, it is argued that the selection of animal models should become more evidence based and that researchers should seize more opportunities to choose or create characteristics in the animal models that increase their predictive value.

In vivo tracking of 111In-oxine labeled mesenchymal stem cells following infusion in patients with advanced cirrhosis

BACKGROUND

Several animal and few human studies suggest the beneficial role of bone marrow mesenchymal stem cells (MSCs) in liver cirrhosis. However, little is known about the fate of MSCs after infusion in cirrhotic patients. We evaluated stem cell biodistribution after peripheral infusion of MSCs in four cirrhotic patients.

METHODS

After three passages of MSCs, the patients received a total of 250-400×10(6) cells, of which only 50% of the cells were labeled. Specific activities of 0.21-0.67 MBq/10(6) cells were maintained for the injected labeled MSCs. Planar whole-body acquisitions (anterior/posterior projections) were acquired immediately following infusion as well as at 2 h, 4 h, 6 h, 24 h, 48 h, 7th and 10th days after cell infusion.

RESULTS

After intravenous infusion, the radioactivity was first observed to accumulate in the lungs. During the following hours to days, the radioactivity gradually increased in the liver and spleen, with spleen uptake exceeding that in the liver in all patients. Region-of-interest analysis showed that the percentage of cells homing to the liver (following decay and background corrections and geometric mean calculation) increased from 0.0%-2.8% at immediately post-infusion images to 13.0-17.4% in 10th-day post-infusion. Similarly, the residual activities in the spleen increased from 2.0%-10.2% at immediately post-infusion images to 30.1%-42.2% in 10th-day post-infusion. During the same period, the residual activities in the lungs decreased from 27.0-33.5% to 2.0-5.4%.

CONCLUSION

The infusion of MSCs labeled with (111)In-oxine through a peripheral vein is safe in cirrhosis. Cell labeling with (111)In-oxine is a suitable method for tracking MSC distribution after infusion.

Automated isolation and processing of adipose-derived stem and regenerative cells

The popularity of nonhematopoietic, adult tissue-derived stem and progenitor cells for use as a cellular research tool, and ultimately as a clinical therapeutic, has increased exponentially over the past decade. Almost all adult-derived stem/progenitor cells (autologous and allogeneic), with one exception, require at least some ex vivo expansion or further manipulation prior to use to satisfy efficacy and safety requirements for preclinical or clinical use. The principal reason is the relatively low frequency of these therapeutically valuable cells within any given adult tissue, except for adipose tissue, which has been shown to have at least two log greater concentrations of these progenitor cells. Therefore, use of autologous adipose-derived cells as both a research tool and cell therapeutic is feasible and has been shown to be both safe and efficacious in preclinical and clinical models of injury and disease. The development and utilization of automated processes and instrumentation such as Cytori Therapeutics' Celution® System to reduce variability and increase quality of the recovered cells is requisite for clinical use and preferred by basic researchers. Here, use of an automated, closed processing platform for isolation and concentration of adipose-derived stem and regenerative cells is described, including a profile of the isolated cells immediately prior to use, and commonly used methods to quantify and qualitatively assess the recovered cells.

Ethical aspects of tissue engineering: a review

Tissue engineering (TE) is a promising new field of medical technology. However, like other new technologies, it is not free of ethical challenges. Identifying these ethical questions at an early stage is not only part of science's responsibility toward society, but also in the interest of the field itself. In this review, we map which ethical issues related to TE have already been documented in the scientific literature. The issues that turn out to dominate the debate are the use of human embryonic stem cells and therapeutic cloning. Nevertheless, a variety of other ethical aspects are mentioned, which relate to different phases in the development of the field. In addition, we discuss a number of ethical issues that have not yet been raised in the literature.

Evaluation of the effect of autologous mesenchymal stem cell injection in a large-animal model of bilateral kidney ischaemia reperfusion injury

OBJECTIVES

Adult mesenchymal stem cells (MSC) have been proven to be of benefit to the kidney in different experimental models of renal injuries. All studies have been performed in valuable rodent models, but the relevance of these results to large mammals and ultimately, to humans remains unknown. Therefore, the aim of this study was to investigate the effect of MSC transplantation in an alternative ovine large-animal model of bilateral kidney ischaemia reperfusion injury.

MATERIAL AND METHODS

Sheep were divided into three groups: one sham-operated group and two groups submitted to renal bilateral ischaemia for 60 min. Animals with ischaemia reperfusion injury were treated with injection of autologous MSCs or with vehicle medium.

RESULTS

The model sheep presented with renal histological manefestations that closely resembled lesions seen in patients. Transplanted MSCs were found in glomeruli but not in tubules and did not express glomerular cell markers (podocin, von Willebrand factor), but functional evaluation showed no beneficial effect of MSC infusion. Morphological and molecular analyses corroborated the functional results. MSCs did not repair kidney parenchyma and failed to modulate cell death and proliferation or cytokine release (tumour necrosis factor-alpha, vascular endothelial growth factor alpha (VEGF-alpha), Bcl-2, caspase).

CONCLUSION

In this unique autologous large-animal model, MSCs did not exhibit reparative or paracrine protective properties.