Substrate Stiffness Modulates Renal Progenitor Cell Properties via a ROCK-Mediated Mechanotransduction Mechanism.

Stem cell (SC)-based tissue engineering and regenerative medicine (RM) approaches may provide alternative therapeutic strategies for the rising number of patients suffering from chronic kidney disease. Embryonic SCs and inducible pluripotent SCs are the most frequently used cell types, but autologous patient-derived renal SCs, such as human CD133+CD24+ renal progenitor cells (RPCs), represent a preferable option. RPCs are of interest also for the RM approaches based on the pharmacological encouragement of in situ regeneration by endogenous SCs. An understanding of the biochemical and biophysical factors that influence RPC behavior is essential for improving their applicability. We investigated how the mechanical properties of the substrate modulate RPC behavior in vitro. We employed collagen I-coated hydrogels with variable stiffness to modulate the mechanical environment of RPCs and found that their morphology, proliferation, migration, and differentiation toward the podocyte lineage were highly dependent on mechanical stiffness. Indeed, a stiff matrix induced cell spreading and focal adhesion assembly trough a Rho kinase (ROCK)-mediated mechanism. Similarly, the proliferative and migratory capacity of RPCs increased as stiffness increased and ROCK inhibition, by either Y27632 or antisense LNA-GapmeRs, abolished these effects. The acquisition of podocyte markers was also modulated, in a narrow range, by the elastic modulus and involved ROCK activity. Our findings may aid in 1) the optimization of RPC culture conditions to favor cell expansion or to induce efficient differentiation with important implication for RPC bioprocessing, and in 2) understanding how alterations of the physical properties of the renal tissue associated with diseases could influenced the regenerative response of RPCs.

Topical Ripasudil Suppresses Retinal Ganglion Cell Death in a Mouse Model of Normal Tension Glaucoma.

Purpose: To assess if ripasudil has a neuroprotective effect using mice with excitatory amino acid carrier 1 (EAAC1) deletion (EAAC1 knockout [KO] mice), a mouse model of normal tension glaucoma. Methods: Topical administration (5 µL/day) of two different concentrations of ripasudil (0.4% and 2%) were applied to EAAC1 KO mice from 5 to 12 weeks old. Optical coherence tomography, multifocal electroretinograms, the measurement of intraocular pressure (IOP), and histopathology analyses were performed at 5, 8, and 12 weeks old. Retrograde labeling of retinal ganglion cells (RGCs), immunoblot, and immunohistochemical analyses of phosphorylated p38 mitogen-activated protein kinase (MAPK) in the retina were performed at 8 weeks old. Results: Topical ripasudil ameliorated retinal degeneration and improved visual function in EAAC1 KO mice at both 8 and 12 weeks old. Ripasudil reduced IOP and strongly suppressed the phosphorylation of p38 MAPK that stimulates RGC death in EAAC1 KO mice. Conclusions: These results suggest that, in addition to IOP reduction, ripasudil prevents glaucomatous retinal degeneration by neuroprotection, which is achieved by suppressing cell-death signaling pathways.

Additive Intraocular Pressure-Lowering Effects of the Rho Kinase Inhibitor Ripasudil (K-115) Combined With Timolol or Latanoprost: A Report of 2 Randomized Clinical Trials.

IMPORTANCE: Ripasudil hydrochloride hydrate (K-115), a novel rho kinase inhibitor, provides statistically significant intraocular pressure (IOP)-lowering effects and has a tolerable safety profile. However, no studies have evaluated ripasudil combined with ß-blockers and prostaglandin analogues. OBJECTIVE: To evaluate the additive IOP-lowering effects and the safety of ripasudil, 0.4%, combined with timolol, 0.5%, or latanoprost, 0.005%, in patients with primary open-angle glaucoma or ocular hypertension. DESIGN, SETTING, AND PARTICIPANTS: We conducted 2, multicenter, randomized, double-masked, parallel group comparison studies of ripasudil-timolol and ripasudil-latanoprost in 29 and 36 Japanese clinical centers, respectively. Analyses were performed on an intention-treat-treat basis. After appropriate run-in periods with timolol or latanoprost, 208 and 205 patients whose IOP levels were 18 mm Hg or higher were enrolled in the ripasudil-timolol and ripasudil-latanoprost groups, respectively. Enrollment began December 1, 2011, and follow-up was completed on September 7, 2012, in the ripasudil-timolol study. Enrollment began December 1, 2011, and follow-up was completed on September 27, 2012, in the ripasudil-latanoprost study. INTERVENTIONS: Patients were subdivided into 2 groups in each study and were treated with ripasudil or placebo twice daily for 8 weeks. MAIN OUTCOMES AND MEASURES: The IOP reductions in the ripasudil and placebo groups were analyzed with a repeated-measures analysis of variance model at weeks 4, 6, and 8, at trough (before instillation [9 am]) and peak (2 hours after instillation [11 am]) levels. RESULTS: In the ripasudil-timolol study, the mean IOP reductions from baseline in the ripasudil and placebo groups were -2.4 and -1.5 mm Hg at 9 am for a difference of 0.9 mm Hg (95% CI, 0.4-1.3 mm Hg; P < .001) and -2.9 and -1.3 mm Hg at 11 am for a difference of 1.6 mm Hg (95% CI, 1.1-2.1 mm Hg; P < .001), respectively. In the ripasudil-latanoprost study, those IOP reductions were -2.2 and -1.8 mm Hg at 9 am for a difference of 0.4 mm Hg (95% CI, -0.0 to 0.9 mm Hg; P = .06) and -3.2 and -1.8 mm Hg at 11 am for a difference of 1.4 mm Hg (95% CI, 0.9-1.9 mm Hg; P < .001), respectively. The most frequently reported adverse event was conjunctival hyperemia, which was mild and in most cases resolved without treatment before the next instillation. CONCLUSIONS AND RELEVANCE: These clinical trials found additive IOP-lowering effects of ripasudil from placebo at trough and peak levels in combination with timolol and at peak level in combination with latanoprost. However, a definitive difference in the addition of placebo to latanoprost was not identified in the trough level. TRIAL REGISTRATION: clinicaltrials.jp Identifiers: JAPIC111700 and JAPIC111701.