Mesenchymal Stem Cell Engineering

Mesenchymal stem cells (MSC) are multipotent stem cells that display the capacity to generate the tissue in which they reside. MSC have been used as progenitor cells to engineer cartilage implants that can be used to repair chondral and osteochondral lesions, or as trophic producers of bioactive factors to initiate endogenous regenerative activities in the arthritic joint. Targeted gene therapy might further enhance the capacity of MSC for chondrogenesis. By using a clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins genomic manipulation technique, target gene-modified MSC would be a promising therapeutic option for regeneration of diseased joints in the treatment of RA.

Sulfasalazine and Chromotrope 2B reduce oxidative stress in murine bone marrow-derived mesenchymal stem cells

BACKGROUND

With advancing age of stem cells, dysregulation of various processes at the cellular level occurs, thereby decreasing their regeneration potential. One of the changes that occurs during the aging process is the accumulation of reactive oxygen species (ROS), which accelerates the processes of cellular senescence and cell death. The aim of this study is to evaluate two antioxidant compounds; Chromotrope 2B and Sulfasalazine, for their antioxidant effects on young and old rat bone marrow mesenchymal stem cells (MSCs).

METHODS AND RESULTS

Oxidative stress was induced in MSCs by 5 µM dexamethasone for 96 h and the cells were treated with Chromotrope 2B or Sulfasalazine, 50 µM each. The effects of antioxidant treatment following oxidative stress induction was evaluated by transcriptional profiling of genes involved in the oxidative stress and telomere maintenance. Expression levels of Cat, Gpx7, Sod1, Dhcr24, Idh1, and Txnrd2 were found to be increased in young MSCs (yMSCs) as a result of oxidative stress, while Duox2, Parp1, and Tert1 expression were found to be decreased as compared to the control. In old MSCs (oMSCs), the expressions of Dhcr24, Txnrd2, and Parp1 increased, while that of Duox2, Gpx7, Idh1, and Sod1 decreased following oxidative stress. In both MSC groups, Chromotrope 2B prompted decrease in the ROS generation before and after the induction of oxidative stress. In oMSCs, ROS content was significantly reduced in the Sulfasalazine treated group.

CONCLUSION

Our findings suggest that both Chromotrope 2B and Sulfasalazine possess the potential to reduce the ROS content in both age groups, though the latter was found to be more potent. These compounds can be used to precondition MSCs to enhance their regenerative potential for future cell-based therapeutics.

Correlation of the regenerative potential of dermal fibroblasts in 2D culture with the biological properties of fibroblast-derived tissue spheroids

In situ 3D bioprinting is a new emerging therapeutic modality for treating human skin diseases. The tissue spheroids have been previously suggested as a powerful tool in rapidly expanding bioprinting technology. It has been demonstrated that the regenerative potential of human dermal fibroblasts could be quantitatively evaluated in 2D cell culture and confirmed after implantation in vivo. However, the development of unbiassed quantitative criteria of the regenerative potential of 3D tissue spheroids in vitro before their in situ bioprinting remains to be investigated. Here it has been demonstrated for the first time that specific correlations exist between the regenerative potential of human dermal fibroblasts cultured in vitro as 2D cell monolayer with biological properties of 3D tissue spheroids fabricated from these fibroblasts. In vitro assessment of biological properties included diameter, spreading and fusion kinetics, and biomechanical properties of 3D tissue spheroids. This comprehensive characterization could be used to predict tissue spheroids' regenerative potential in vivo.

Insight into generation of induced mesenchymal stem cells from induced pluripotent cells

Mesenchymal stem cells (MSCs) have the potential for use in cell-based regenerative therapies. Currently, hundreds of clinical trials are using MSCs for the treatment of various diseases. However, MSCs are low in number in adult tissues; they show heterogeneity depending upon the cell source and exhibit limited proliferative potential and early senescence in in vitro cultures. These factors negatively impact the regenerative potential of MSCs and therefore restrict their use for clinical applications. As a result, novel methods to generate induced MSCs (iMSCs) from induced pluripotent stem cells have been explored. The development and optimization of protocols for generation of iMSCs from induced pluripotent stem cells is necessary to evaluate their regenerative potential in vivo and in vitro. In addition, it is important to compare iMSCs with primary MSCs (isolated from adult tissues) in terms of their safety and efficacy. Careful investigation of the properties of iMSCs in vitro and their long term behavior in animals is important for their translation from bench to bedside.

Applications of the regenerative capacity of platelets in modern medicine

Platelets produce platelet growth factors such as PDGF, IGF-1, EGF-, HGF, TGFβ, bFGF, and VEGF, which are crucial in regulating all stages of the wound healing process. The source of these substances is platelet-rich plasma (PRP). Over the past five decades, the interest and use of the regenerative properties of platelets have increased significantly in many different fields of medicine around the world. PRP and PRF plate preparations are used in: 1. Dentistry (they reduce bleeding, facilitate and accelerate soft tissue healing and bone regeneration - FGF 2, IGF-1, IGF-2, TGF-β1, and PDGF); 2. Sports medicine - IGF-1, IGF-2, TGF-β, VEGF, PDGF and bFGF, EGF); 3. dermatology and cosmetology (treatment of alopecia, hair reconstruction - FGF-7, HGF, acne scars, skin rejuvenation and regeneration, treatment of chronic and poorly healing wounds, burns, and acquired vitiligo); 4. Gynecology and reproductive medicine (treatment of infertility, erectile dysfunction - PDGF-β, TGF-β, IGF-1, in sexual dysfunction - PDGF, in vaginal atrophy); 5 Ophthalmology (in the healing of corneal epithelial wounds, in the treatment of dormant corneal ulcers, dry eye syndrome and the reconstruction of the corneal surface; 6. Neurology (regeneration of neurons, pain alleviation, and clinical symptoms - TGF-β 1, IGF-1, PDGF, VEGF) and FGF). Platelet-rich plasma therapy is a very interesting alternative and complement to traditional methods of treatment. However, the potential for using platelets is still not fully understood. The composition of platelet-rich plasma depends on many factors that may affect its use's efficacy and clinical benefits. Further research is necessary to standardize PRP delivery's preparation procedures and methods for a specific disease entity or clinical case.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

Regenerative Potential of DPSCs and Revascularization: Direct, Paracrine or Autocrine Effect?

A new source of mesenchymal stem cells has recently been discovered, the so-called dental pulp derived stem cells (DPSCs) which therefore could represent potentially tools for regenerative medicine. DPSC originate from the neural crest and are physiologically involved in dentin homeostasis; moreover, they contribute to bone remodeling and differentiation into several tissues including cartilage, bone, adipose and nervous tissues. DPSCs have also been shown to influence the angiogenesis process, for example through the release of secretory factors or by differentiating into vascular and/or perivascular cells. Angiogenesis, that has a pivotal role in tissue regeneration and repair, is defined as the formation of new vessels from preexisting vessels and is mediated by mutual and reciprocal interactions between endothelial cells and perivascular cells. It is also known that co-cultures of perivascular and endothelial cells (ECs) can form a vascular network in vitro and also in vivo. Since DPSCs seem to have characteristics similar to pericytes, understanding the possible mechanism of interaction between DPSCs and ECs during neo-angiogenesis is dramatically important for the development of advanced clinical application in the field of regeneration.

Stem cell plasticity and regenerative potential regulation through Ca2+-mediated mitochondrial nuclear crosstalk

The multi-lineage differentiation potential is one of the prominent mechanisms through which stem cells can repair damaged tissues. The regenerative potential of stem cells is the manifestation of several changes at the structural and molecular levels in stem cells that are regulated through intricate mitochondrial-nuclear interactions maintained by Ca²⁺ ion signaling. Despite the exhilarating evidences strengthening the versatile and indispensible role of Ca²⁺ in regulating mitochondrial-nuclear interactions, the extensive details of signaling mechanisms remains largely unexplored. In this review we have discussed the effect of Ca²⁺ ion mediated mitochondrial-nuclear interactions participating in stem plasticity and its regenerative potential.

Mitochondrial donation in translational medicine; from imagination to reality

The existence of active crosstalk between cells in a paracrine and juxtacrine manner dictates specific activity under physiological and pathological conditions. Upon juxtacrine interaction between the cells, various types of signaling molecules and organelles are regularly transmitted in response to changes in the microenvironment. To date, it has been well-established that numerous parallel cellular mechanisms participate in the mitochondrial transfer to modulate metabolic needs in the target cells. Since the conception of stem cells activity in the restoration of tissues’ function, it has been elucidated that these cells possess a unique capacity to deliver the mitochondrial package to the juxtaposed cells. The existence of mitochondrial donation potentiates the capacity of modulation in the distinct cells to achieve better therapeutic effects. This review article aims to scrutinize the current knowledge regarding the stem cell’s mitochondrial transfer capacity and their regenerative potential.

Single-cell RNA sequencing reveals the regenerative potential of thyroid follicular epithelial cells in metastatic thyroid carcinoma

Thyroid stimulating hormone deficiency is the cornerstone of treatment for metastatic thyroid cancer. Due to the loss of follicular epithelial cells in thyroid cancer, the thyroid gland degenerates to 85% of its original size. When thyroid stimulating hormone is restored, follicular epithelial cells in thyroid cancer regenerate, which is postulated to be related to stem-like cells. By single cell RNA seq, we found a group of rare thyroid follicular epithelial cells in mouse metastatic thyroid cancer, which expressed stem-like genes (CD44V6⁺ and CD133⁺) and a large number of differentiated cells (CD44V6⁺ and CD24⁺). In mouse and in organoids, the two subsets contribute equally to metastatic thyroid cancer regeneration. The analysis of human metastatic thyroid cancer revealed that the differentiated thyroid follicular epithelial cell subpopulation was similar to that of the stem like epithelial cell subpopulation, and the regeneration potential was also enhanced after thyroid stimulating hormone ablation. Accordingly, we propose that the regeneration of metastatic thyroid cancer is driven by almost all persistent thyroid follicular epithelial cells, not only by few stem-like cells.

Mechanisms underlying the protective effects of mesenchymal stem cell-based therapy. Cell Mol Life Sci. 2020;77:2771-2794. [PMID: 31965214 PMCID: PMC7223321 DOI: 10.1007/s00018-020-03454-6]

Mesenchymal stem cells (MSCs) have been extensively investigated for the treatment of various diseases. The therapeutic potential of MSCs is attributed to complex cellular and molecular mechanisms of action including differentiation into multiple cell lineages and regulation of immune responses via immunomodulation. The plasticity of MSCs in immunomodulation allow these cells to exert different immune effects depending on different diseases. Understanding the biology of MSCs and their role in treatment is critical to determine their potential for various therapeutic applications and for the development of MSC-based regenerative medicine. This review summarizes the recent progress of particular mechanisms underlying the tissue regenerative properties and immunomodulatory effects of MSCs. We focused on discussing the functional roles of paracrine activities, direct cell-cell contact, mitochondrial transfer, and extracellular vesicles related to MSC-mediated effects on immune cell responses, cell survival, and regeneration. This will provide an overview of the current research on the rapid development of MSC-based therapies.

Mesenchymal Stem Cell Engineering

Mesenchymal stem cells (MSC) are multipotent stem cells that display the capacity to generate the tissue in which they reside. MSC have been used as progenitor cells to engineer cartilage implants that can be used to repair chondral and osteochondral lesions, or as trophic producers of bioactive factors to initiate endogenous regenerative activities in the arthritic joint. Targeted gene therapy might further enhance the capacity of MSC for chondrogenesis. By using a clustered regularly interspaced short palindromic repeats/CRISPR-associated protein genomic manipulation technique, target-gene-modified MSC would be a promising therapeutic option for regeneration of diseased joints in the treatment of RA.

Regenerative potential of the cartilaginous tissue in mesenchymal stem cells: update, limitations, and challenges

Advances in the studies with adult mesenchymal stem cells (MSCs) have turned tissue regenerative therapy into a promising tool in many areas of medicine. In orthopedics, one of the main challenges has been the regeneration of cartilage tissue, mainly in diarthroses. In the induction of the MSCs, in addition to cytodifferentiation, the microenvironmental context of the tissue to be regenerated and an appropriate spatial arrangement are extremely important factors. Furthermore, it is known that MSC differentiation is fundamentally determined by mechanisms such as cell proliferation (mitosis), biochemical-molecular interactions, movement, cell adhesion, and apoptosis. Although the use of MSCs for cartilage regeneration remains at a research level, there are important questions to be resolved in order to make this therapy efficient and safe. It is known, for instance, that the expansion of chondrocytes in cultivation, needed to increase the number of cells, could end up producing fibrocartilage instead of hyaline cartilage. However, the latest results are promising. In 2014, the first stage I/II clinical trial to evaluate the efficacy and safety of the intra-articular injection of MSCs in femorotibial cartilage regeneration was published, indicating a decrease in injured areas. One issue to be explored is how many modifications in the articulate inflammatory environment could induce differentiation of MSCs already allocated in that region. Such issue arose from studies that suggested that the suppression of the inflammation may increase the efficiency of tissue regeneration. Considering the complexity of the events related to the chondrogenesis and cartilage repair, it can be concluded that the road ahead is still long, and that further studies are needed.

Quantification of regenerative potential in primary human mammary epithelial cells

We present an organoid regeneration assay in which freshly isolated human mammary epithelial cells are cultured in adherent or floating collagen gels, corresponding to a rigid or compliant matrix environment. In both conditions, luminal progenitors form spheres, whereas basal cells generate branched ductal structures. In compliant but not rigid collagen gels, branching ducts form alveoli at their tips, express basal and luminal markers at correct positions, and display contractility, which is required for alveologenesis. Thereby, branched structures generated in compliant collagen gels resemble terminal ductal-lobular units (TDLUs), the functional units of the mammary gland. Using the membrane metallo-endopeptidase CD10 as a surface marker enriches for TDLU formation and reveals the presence of stromal cells within the CD49f(hi)/EpCAM(-) population. In summary, we describe a defined in vitro assay system to quantify cells with regenerative potential and systematically investigate their interaction with the physical environment at distinct steps of morphogenesis.

C-kit(+) cells isolated from developing kidneys are a novel population of stem cells with regenerative potential

The presence of tissue specific precursor cells is an emerging concept in organ formation and tissue homeostasis. Several progenitors are described in the kidneys. However, their identity as a true stem cell remains elusive. Here, we identify a neonatal kidney-derived c-kit(+) cell population that fulfills all of the criteria as a stem cell. These cells were found in the thick ascending limb of Henle's loop and exhibited clonogenicity, self-renewal, and multipotentiality with differentiation capacity into mesoderm and ectoderm progeny. Additionally, c-kit(+) cells formed spheres in nonadherent conditions when plated at clonal density and expressed markers of stem cells, progenitors, and differentiated cells. Ex vivo expanded c-kit(+) cells integrated into several compartments of the kidney, including tubules, vessels, and glomeruli, and contributed to functional and morphological improvement of the kidney following acute ischemia-reperfusion injury in rats. Together, these findings document a novel neonatal rat kidney c-kit(+) stem cell population that can be isolated, expanded, cloned, differentiated, and used for kidney repair following acute kidney injury. These cells have important biological and therapeutic implications.

Muscle 'regenerative potential' determinesphysical recovery following total knee replacement

Objectives

Lower limb muscle power is thought to influence outcome following total knee replacement (TKR). Post-operative deficits in muscle strength are commonly reported, although not explained. We hypothesised that post-operative recovery of lower limb muscle power would be influenced by the number of satellite cells in the quadriceps muscle at time of surgery.

Methods

Biopsies were obtained from 29 patients undergoing TKR. Power output was assessed pre-operatively and at six and 26 weeks post-operatively with a Leg Extensor Power Rig and data were scaled for body weight. Satellite cell content was assessed in two separate analyses, the first cohort (n = 18) using immunohistochemistry and the second (n = 11) by a new quantitative polymerase chain reaction (q-PCR) protocol for Pax-7 (generic satellite cell marker) and Neural Cell Adhesion Molecule (NCAM; marker of activated cells).

Results

A significant improvement in power output was observed post-operatively with a mean improvement of 19.7 W (95% confidence interval (CI) 14.43 to 30.07; p < 0.001) in the first cohort and 27.5 W (95% CI 13.2 to 41.9; p = 0.002) in the second. A strong correlation was noted between satellite cell number (immunohistochemistry) and improvement in patient power output (r = 0.64, p = 0.008). Strong correlation was also observed between the expression of Pax-7 and power output (r = 0.79, p = 0.004), and the expression of NCAM and power output (r = 0.84, p = 0.001). The generic marker explained 58% of the variation in power output, and the marker of activated cells 67%.

Conclusions

Muscle satellite cell content may determine improvement in lower limb power generation (and thus function) following TKR.