Mechanobiological Conditioning of Mesenchymal Stem Cells Enhances Therapeutic Angiogenesis by Inducing a Hybrid Pericyte-Endothelial Phenotype

Abstract

Stem cell therapies have great promise for revolutionizing treatments for cardiovascular disease and other disorders but have not yet achieved their potential due to poor efficacy and heterogeneity in patient response. Here, we used a novel high throughput screening system to optimize the conditioning of mesenchymal stem cells using a combinatorial set of biochemical factors, pharmacological inhibitors and biomechanical forces. Our studies revealed that a combination of specific kinase inhibitors and a complex mechanical strain waveform dramatically increased the population of mesenchymal stem cells that express markers for both pericytes and endothelial cells. These mechanically and pharmacologically conditioned mesenchymal stem cells had superior properties in enhancing endothelial tube formation, production of angiogenic growth factors and induction of angiogenesis following implantation.Overall, our work supports that combinatorial optimization of mechanical conditioning and pharmacological treatments can significantly enhance the regenerative properties of mesenchymal stem cells. Page 3 of 65Cell based therapies have great potential for revolutionizing the treatment of diseases that are not amenable to traditional treatments. Therapies based on mesenchymal stem cells (MSCs) are particularly appealing as they are a source of autologous cells with diverse multipotency and can be harvested from patients with relative ease. In addition, MSCs are able to self-renew and have immunosuppressive properties that make them ideal candidates for autologous cellular therapeutics 1 . For cardiovascular therapies, MSCs have been explored for the treatment of myocardial infarct and peripheral ischemia 2-7 . However, these trials have not shown consistent long-term benefits to patients from MSC therapies in spite of intense investigation by many groups [8][9][10][11] . MSCs have several aspects that limit their potential for use in cell therapies. In conventional culture conditions, MSCs lose their differentiation potential and have reduced therapeutic properties after expansion 12,13 . In addition, the isolated MSC populations have a high degree of heterogeneity, with subsets of cells that have varying degrees of potential for inducing regeneration 14,15 . Moreover, the therapeutic potential of MSCs is altered by the health of the patient from which they are harvested. This is a major limitation as patients with advanced age, obesity, diabetes and other chronic disorders have MSCs with altered differentiation potential and regenerative properties 12,13,[16][17][18][19] . Thus, those patients who would likely benefit the most from cell therapies are those who have the least regenerative MSCs. Genetic modification of MSCs could address some of these issues but also raise concerns of tumorigenicity 20 . Consequently, there is an intense interest in identifying alternative strategies for making MSCs more effective and reliable in spite of patient-to-patient differences in MSC behavior or reduced regenerative capability.The diffe...

Mechanical Rejuvenation of Mesenchymal Stem Cells from Aged Patients

“…28 This work demonstrated that mechanical loading with a physiological waveform (brachial waveform) at 7.5% mechanical strain in combination with a EGFR/ErbB2-4 (E/E) inhibitor leads to enhanced MSC production of soluble HGF, increases endothelial cell and pericyte markers, and pericyte-like functionality in MSCs. 28 Using a high throughput biaxial oscillatory stretch system (HT-BOSS) developed in our laboratory, [29][30][31] we explore the effect of these loading conditions on senescence in MSCs derived from aged donors (68-92 years old). We found that mechanical conditioning led to a lasting enhancement of proliferative function, expansion capacity, multipotency, and reduction of senescence in MSCs from aged donors.…”