Generation of cortical neurons from human induced-pluripotent stem cells by biodegradable polymeric microspheres loaded with priming factors

Abstract

Ischemic stroke is often associated with loss of cortical neurons leading to various neurological deficits. A cell replacement based on stem cell transplantation to repair the damaged brain requires the generation of specific neuronal subtypes. Recently, induced pluripotent stem cells have been used to generate various subtypes of neurons in vitro for transplantation in stroke-damaged brains. However, whether these cells can be primed as neuronal precursors to become cortical projection neurons by means of biomaterials releasing differentiation factors is not known. Here, we report that microspheres of biodegradable poly(ester-amide) composed of adipic acid, L-phenyl-alanine and 1,4-butanediol, loaded with differentiation factors, can be used to fate human induced pluripotent stem cell-derived long-term expandable neuroepithelial-like stem cells to cortical projection neurons. The three factors, Wnt3A, BMP4 and cyclopamine, were released from loaded microspheres over at least one month following biphasic dynamic time course, promoting cortical differentiation of the cells in vitro. Microspheres did not evoke significant inflammatory response after transplantation into intact rodent brain. Our study shows the potential of biodegradable polymer microspheres to promote neuronal differentiation by continuous release of factors, thereby creating the appropriate microenvironment. This new strategy may improve the efficacy of stem cell-based therapeutic approaches.

Restoring brain function after stroke — bridging the gap between animals and humans

“…Most of the compounds discussed have been administered via intravenous or intrathecal routes, but accurate spatial and temporal delivery might both be necessary to achieve the desired outcomes. Advances made in the last few years in tissue engineering 35,36 and optogenetics 37 provide potential methods for precisely delivering regenerative molecules to functionally relevant brain regions.…”

Biomaterial Engineering for Controlling Pluripotent Stem Cell Fate

“…In 2D differentiation cultures, the required amount of growth factors can become expensive and unrealistic for high volume systems. Alternatively, a more economical approach is to immobilize signals within a 3D biomaterial or encapsulate growth factors for localized release [94, 95]. In one study, growth factor encapsulation within 3D, degradable polymeric microparticles led to a 10-fold reduction in total growth factor needed to stimulate comparable gene expression to soluble treatment in 2D cultures [95].…”

The Role of Biomaterials in Implantation for Central Nervous System Injury

“…After the microspheres had been incubated with hiPSC-derived neuroepithelial-like stem cells, cortical differentiation of the cells was observed in vitro. Moreover, the biodegradable poly(ester-amide) microspheres did not evoke a significant inflammatory response after transplantation into an intact rodent brain 38 .…”