Different modes of foveal regeneration after closure of full-thickness macular holes by(re)vitrectomy and autologous platelet concentrate

AIM: To describe using spectral-domain optical coherence tomography the regeneration of the foveal morphology after pars plana(re)vitrectomy surgery and gas tamponade combined with injection of autologous platelet concentrate to treat full-thickness macular holes, and to describe different anatomical outcome. METHODS: A retrospective case series of 8 eyes of 8 patients was described. RESULTS: In all cases investigated, the plateletassisted closure of macular holes was associated with a rapid resolution of cystic cavities in the foveal walls. In two patients, there was a regular regeneration of the foveal morphology after hole closure;the regenerated central fovea had a regular structure with a foveola and photoreceptors. In three other patients, there was an irregular regeneration of the fovea;a foveola was not formed, photoreceptor cells were absent from the foveal center, and the center was composed of Müller and retinal pigment epithelial(RPE) cells. The foveal regeneration after hole closure may proceed with or without a temporary detachment of the foveal center from the RPE, and with or without a direct contact between the central outer nuclear layer(ONL) and the RPE. Contacts between the ONL and RPE were observed only in patients with an irregular foveal regeneration after hole closure.CONCLUSION: The data show that there are different modes of foveal regeneration after closure of macular holes with(re)vitrectomy and platelet concentrate. It is suggested that the regular regeneration of the foveal morphology proceeds by Müller cell-mediated tissue movements without cell proliferation, whereas the irregular foveal regeneration proceeds in part by proliferation of Müller and RPE cells.

Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall.In our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses.In order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow conditions.The numerical models were created based on our previous experimental studies.The simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion tube.The present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.

Induced Pluripotent Stem Cell-derived Mesenchymal Stem Cell Seeding on Biofunctionalized Calcium Phosphate Cements

Induced pluripotent stem ceils （iPSCs） have great potential due to their proliferation and differentiation capability. The objectives of this study were to generate iPSC-derived mesenchymal stem cells （iPSC-MSCs）, and investigate iPSC-MSC proliferation and osteogenic differentiation on calcium phosphate cement （CPC） containing biofunctional agents for the first time. Human iPSCs were derived from marrow CD34＋ cells which were reprogrammed by a single episomal vector, iPSCs were cultured to form embryoid bodies （EBs）, and MSCs migrated out of EBs. Five biofunctional agents were incorporated into CPC： RGD （Arg-Gly-Asp） peptides, fibronectin （Fn）, fibronectin-like engineered polymer protein （FEPP）, extracellular matrix Geltrex, and platelet concentrate, iPSC-MSCs were seeded on five biofunctionalized CPCs： CPC-RGD, CPC-Fn, CPC- FEPP, CPC-Geltrex, and CPC-Platelets. iPSC-MSCs on biofunctional CPCs had enhanced proliferation, actin fiber expression, osteogenic differentiation and mineralization, compared to control. Cell proliferation was greatly increased on biofunctional CPCs. iPSC-MSCs underwent osteogenic differentiation with increased alkaline phosphatase, Runx2 and coUagen-I expressions. Mineral synthesis by iPSC-MSCs on CPC-Platelets was 3-fold that of CPC control. In conclusion, iPSCs showed high potential for bone engineering, iPSC- MSCs on biofunctionalized CPCs had cell proliferation and bone mineralization that were much better than traditional CPC. iPSC-MSC-CPC constructs are promising to promote bone regeneration in craniofacial/ orthopedic repairs.