TGF-β1 Suppresses Proliferation and Induces Differentiation in Human iPSC Neural in vitro Models

Abstract

Persistent neural stem cell (NSC) proliferation is, among others, a hallmark of immaturity in human induced pluripotent stem cell (hiPSC)-based neural models. TGF-β1 is known to regulate NSCs in vivo during embryonic development in rodents. Here we examined the role of TGF-β1 as a potential candidate to promote in vitro differentiation of hiPSCs-derived NSCs and maturation of neuronal progenies. We present that TGF-β1 is specifically present in early phases of human fetal brain development. We applied confocal imaging and electrophysiological assessment in hiPSC-NSC and 3D neural in vitro models and demonstrate that TGF-β1 is a signaling protein, which specifically suppresses proliferation, enhances neuronal and glial differentiation, without effecting neuronal maturation. Moreover, we demonstrate that TGF-β1 is equally efficient in enhancing neuronal differentiation of human NSCs as an artificial synthetic small molecule. The presented approach provides a proof-of-concept to replace artificial small molecules with more physiological signaling factors, which paves the way to improve the physiological relevance of human neural developmental in vitro models.

Ontogeny of oscillatory slow-wave and neuronal population activity in human iPSC-3D cortical circuits

“…video 1). For an extensive cellular and electrophysiological characterization of our human iPSC-3DNA experimental model see previous work ( 21, 22, 25 ).…”

“…To obtain 3DNAs, we used the "dual-SMAD inhibition" protocol for neural induction of human iPSCs to obtain neural rosettes comprising neural stem cells with a dorsal telencephalic identity (fig. 1A, (21)(22)(23)(24)), which were stored as cryostocks of human iPSC-cortical neural stem cells. After thawing and re-plating, neural stem cells formed neural rosettes and individual neural rosettes gave rise to 3D neural aggregates (21)(22)(23).…”

“…1A, (21)(22)(23)(24)), which were stored as cryostocks of human iPSC-cortical neural stem cells. After thawing and re-plating, neural stem cells formed neural rosettes and individual neural rosettes gave rise to 3D neural aggregates (21)(22)(23). 3D neural aggregates comprised cortical neurons (fig.…”

“…For low-frequency LFP analysis, raw MEA signals sampled at 25 kHz were first downsampled to 1 kHz. For time domain analysis of local field potential oscillations, we separately determined five slowly varying time domain signal parts in the five frequency bands delta (1-4 Hz), theta (4-11 Hz), beta (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), gamma (30-55 Hz) and high gamma (55-100 Hz). In supplementary figure 1 A (i) to (iv), we present the FIR filter magnitude (dB) and phase (° degrees) response functions for the frequency bands delta, theta, beta and gamma.…”

“…Depending on the type of electrode and its relative position to the cellular source, such electrodes can record electrical signals in the form of spikes (corresponding to action potentials) or oscillatory slow-wave activity, local field potentials (LFPs). Since Hans Berger's first electroencephalogram (EEG) recordings in adult humans using extracranial scalp electrodes in 1929 (1), oscillatory slow-wave activity has been analyzed in traditional frequency bands like slow-oscillatory (< 1 Hz), delta (1-4 Hz), theta (4)(5)(6)(7)(8)(9)(10)(11), beta (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), gamma and high gamma (55-100 Hz). Sensorimotor function, speech, memory, perception, cognition and behavior-all brain information processing is accompanied by characteristic brain wave activity, reflected in the composition, power, and duration of neuronal local field potentials in these frequency bands.…”