Age-related changes in human skeletal muscle transcriptome and proteome are more affected by chronic inflammation and physical inactivity than primary aging.

Evaluation of the influence of primary and secondary aging on the manifestation of molecular and cellular hallmarks of aging is a challenging and currently unresolved issue. Our study represents the first demonstration of the distinct role of primary aging and chronic inflammation/physical inactivity - the most important drivers of secondary aging, in the regulation of transcriptomic and proteomic profiles in human skeletal muscle. To achieve this purpose, young healthy people (n = 15), young (n = 8) and older (n = 37) patients with knee/hip osteoarthritis, a model to study the effect of long-term inactivity and chronic inflammation on the vastus lateralis muscle, were included in the study. It was revealed that widespread and substantial age-related changes in gene expression in older patients relative to young healthy people (~4000 genes regulating mitochondrial function, proteostasis, cell membrane, secretory and immune response) were related to the long-term physical inactivity and chronic inflammation rather than primary aging. Primary aging contributed mainly to the regulation of genes (~200) encoding nuclear proteins (regulators of DNA repair, RNA processing, and transcription), mitochondrial proteins (genes encoding respiratory enzymes, mitochondrial complex assembly factors, regulators of cristae formation and mitochondrial reactive oxygen species production), as well as regulators of proteostasis. It was found that proteins associated with aging were regulated mainly at the post-transcriptional level. The set of putative primary aging genes and their potential transcriptional regulators can be used as a resource for further targeted studies investigating the role of individual genes and related transcription factors in the emergence of a senescent cell phenotype.

Influence of PHA Substrate Surface Characteristics on the Functional State of Endothelial Cells.

The needs of modern regenerative medicine for biodegradable polymers are wide and varied. Restoration of the viability of the vascular tree is one of the most important components of the preservation of the usefulness of organs and tissues. The creation of vascular implants compatible with blood is an important task of vascular bioengineering. The function of the endothelial layer of the vessel, being largely responsible for the development of thrombotic complications, is of great importance for hemocompatibility. The development of surfaces with specific characteristics of biomaterials that are used in vascular technologies is one of the solutions for their correct endothelialization. Linear polyhydroxyalkanoates (PHAs) are biodegradable structural polymeric materials suitable for obtaining various types of implants and tissue engineering, having a wide range of structural and physicomechanical properties. The use of PHA of various monomeric compositions in endothelial cultivation makes it possible to evaluate the influence of material properties, especially surface characteristics, on the functional state of cells. It has been established that PHA samples with the inclusion of 3-hydroxyhexanoate have optimal characteristics for the formation of a human umbilical vein endothelial cell, HUVEC, monolayer in terms of cell morphology as well as the levels of expression of vinculin and VE-cadherin. The obtained results provide a rationale for the use of PHA copolymers as materials for direct contact with the endothelium in vascular implants.

Mesenchymal Stromal Cells as Critical Contributors to Tissue Regeneration.

Adult stem cells that are tightly regulated by the specific microenvironment, or the stem cell niche, function to maintain tissue homeostasis and regeneration after damage. This demands the existence of specific niche components that can preserve the stem cell pool in injured tissues and restore the microenvironment for their subsequent appropriate functioning. This role may belong to mesenchymal stromal cells (MSCs) due to their resistance to damage signals and potency to be specifically activated in response to tissue injury and promote regeneration by different mechanisms. Increased amount of data indicate that activated MSCs are able to produce factors such as extracellular matrix components, growth factors, extracellular vesicles and organelles, which transiently substitute the regulatory signals from missing niche cells and restrict the injury-induced responses of them. MSCs may recruit functional cells into a niche or differentiate into missing cell components to endow a niche with ability to regulate stem cell fates. They may also promote the dedifferentiation of committed cells to re-establish a pool of functional stem cells after injury. Accumulated evidence indicates the therapeutic promise of MSCs for stimulating tissue regeneration, but the benefits of administered MSCs demonstrated in many injury models are less than expected in clinical studies. This emphasizes the importance of considering the mechanisms of endogenous MSC functioning for the development of effective approaches to their pharmacological activation or mimicking their effects. To achieve this goal, we integrate the current ideas on the contribution of MSCs in restoring the stem cell niches after damage and thereby tissue regeneration.

Unveiling Mesenchymal Stromal Cells' Organizing Function in Regeneration.

Regeneration is a fundamental process attributed to the functions of adult stem cells. In the last decades, delivery of suspended adult stem cells is widely adopted in regenerative medicine as a leading means of cell therapy. However, adult stem cells cannot complete the task of human body regeneration effectively by themselves as far as they need a receptive microenvironment (the niche) to engraft and perform properly. Understanding the mechanisms underlying mammalian regeneration leads us to an assumption that improved outcomes of cell therapy require a specific microenvironment that is generated in damaged areas prior to stem cell delivery. To a certain extent, it may be achieved by the delivery of mesenchymal stromal cells (MSCs), not in dispersed form, but rather in self-organized cell sheets (CS) ⁻ tissue-like structures comprised of viable cells and microenvironment components: extracellular matrix and soluble factors deposited in the matrix. In this review, we highlight the potential role of MSCs as regeneration organizers and speculate that this function emerges in CS. This concept shifts our understanding of the therapeutic mechanism underlying a widely known CS-based delivery method for regenerative medicine.

Enhanced angiogenesis in ischemic skeletal muscle after transplantation of cell sheets from baculovirus-transduced adipose-derived stromal cells expressing VEGF165.

INTRODUCTION: Cell therapy using adipose-derived stromal cells (ADSC) is an intensively developing approach to promote angiogenesis and regeneration. Administration technique is crucial and among others minimal constructs - cell sheets (CS) have certain advantages. Delivery of CS allows transplantation of cells along with matrix proteins to facilitate engraftment. Cells' therapeutic potential can be also increased by expression of proangiogenic factors by viral transduction. In this work we report on therapeutic efficacy of CS from mouse ADSC transduced to express human vascular endothelial growth factor 165 a/a isoform (VEGF165), which showed potency to restore perfusion and protect tissue in a model of limb ischemia. METHODS: Mouse ADSC (mADSC) isolated from C57 male mice were expanded for CS formation (10(6)cells per CS). Constructs were transduced to express human VEGF165 by baculoviral (BV) system. CS were transplanted subcutaneously to mice with surgically induced limb ischemia and followed by laser Doppler perfusion measurements. At endpoint animals were sacrificed and skeletal muscle was evaluated for necrosis and vessel density; CS with underlying muscle was stained for apoptosis, proliferation, monocytes and blood vessels. RESULTS: Using BV system and sodium butyrate treatment we expressed human VEGF165 in mADSC (production of VEGF165 reached ≈ 25-27 ng/ml/10(5) cells) and optimized conditions to ensure cells' viability after transduction. Implantation of mock-transduced CS resulted in significant improvement of limb perfusion, increased capillary density and necrosis reduction at 2 weeks post-surgery compared to untreated animals. Additional improvement of blood flow and angiogenesis was observed after transplantation of VEGF165-expressing CS indicating enhanced therapeutic potential of genetically modified constructs. Moreover, we found delivery of mADSC as CS to be superior to equivalent dose of suspended cells in terms of perfusion and angiogenesis. Histology analysis of extracted CS detected limited proliferation and approximately 10 % prevalence of apoptosis in transplanted mADSC. Significant vascularization of CS and infiltration by monocytes were found in both - BV-transduced and control CS indicating graft and host interaction after transplantation. CONCLUSIONS: Delivery of ADSC by subcutaneous transplantation of CS is effective for stimulation of angiogenesis and tissue protection in limb ischemia with a potential for efficacy improvement by BV transduction to express VEGF165.

Autologous Stem Cell Therapy: How Aging and Chronic Diseases Affect Stem and Progenitor Cells.

During recent years different types of adult stem/progenitor cells have been successfully applied for the treatment of many pathologies, including cardiovascular diseases. The regenerative potential of these cells is considered to be due to their high proliferation and differentiation capacities, paracrine activity, and immunologic privilege. However, therapeutic efficacy of the autologous stem/progenitor cells for most clinical applications remains modest, possibly because of the attenuation of their regenerative potential in aged patients with chronic diseases such as cardiovascular diseases and metabolic disorders. In this review we will discuss the risk factors affecting the therapeutic potential of adult stem/progenitor cells as well as the main approaches to mitigating them using the methods of regenerative medicine.

Disturbed angiogenic activity of adipose-derived stromal cells obtained from patients with coronary artery disease and diabetes mellitus type 2.

BACKGROUND: Multipotent mesenchymal stem/stromal cells (MSC) including adipose-derived stromal cells (ADSC) have been successfully applied for cardiovascular diseases treatment. Their regenerative potential is considered due to the multipotency, paracrine activity and immunologic privilege. However, therapeutic efficacy of autologous MSC for myocardial ischemia therapy is modest. We analyzed if ADSC properties are attenuated in patients with chronic diseases such as coronary artery disease (CAD) and diabetes mellitus type 2 (T2DM). METHODS AND RESULTS: ADSC were isolated from subcutaneous fat tissue of patients without established cardiovascular diseases and metabolic disorders (control group, n = 19), patients with CAD only (n = 32) and patients with CAD and T2DM (n = 28). ADSC phenotype (flow cytometry) was CD90(+)/CD73(+)/CD105(+)/CD45(-)/CD31(-) and they were capable of adipogenic and osteogenic differentiation. ADSC morphology and immunophenotype were similar for all patients, but ADSC from patients with CAD and T2DM had higher proliferation activity and shorter telomeres compared to control patients. ADSC conditioned media stimulated capillary-like tubes formation by endothelial cells (EA.hy926), but this effect significantly decreased for patients with CAD (p = 0.03) and with CAD + T2DM (p = 0.017) compared to the control group. Surprisingly we revealed significantly higher secretion of some pro-angiogenic factors (ELISA) by ADSC: vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) for patients with CAD and HGF and placental growth factor (PlGF) for patients with CAD + T2DM. Among angiogenesis inhibitors such as thrombospondin-1, endostatin and plasminogen activator inhibitor-1 (PAI-1) level of PAI-1 in ADSC conditioned media was significantly higher for patients with CAD and CAD + T2DM compared to the control group (p < 0.01). Inhibition of PAI-1 in ADSC conditioned media by neutralizing antibodies partially restored ADSC angiogenic activity (p = 0.017). CONCLUSIONS: ADSC angiogenic activity is significantly declined in patients with CAD and T2DM, which could restrict the effectiveness of autologous ADSC cell therapy in these cohorts of patients. This impairment might be due to the disturbance in coordinated network of pro- and anti-angiogenic growth factors secreted by ADSC. Changes in ADSC secretome differ between patients with CAD and T2DM and further investigation are necessary to reveal the MSC-involved mechanisms of cardiovascular and metabolic diseases and develop novel approaches to their correction using the methods of regenerative medicine.