An Implantable Wireless Optogenetic Stimulation System for Peripheral Nerve Control
2015 37TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC)
Authors: Song, Kang-Il; Park, Sunghee E.; Kim, Myoung-Soo; Joo, Chulmin; Kim, Yong-Jun; Suh, Jun-Kyo F.; Hwang, Dosik; Youn, Inchan
Abstract
An implantable wireless optogenetic stimulation system with an LED-based optical stimulation cuff electrode was developed for peripheral nerve control. The proposed system consisted of a battery-powered optical cuff electrode, optical stimulation controller, and wireless communication system. The optical cuff electrode had a polydimethylsiloxane (PDMS) structure was designed to illuminate the entire sciatic nerve. The wireless communication system was designed to comply with medical implant communication service (MICS) regulations. To evaluate the proposed system, optogenetic stimulation was performed in optogenetic transgenic mice (Thy1::ChR2). The optical cuff electrode was implanted on the sciatic nerve, and movement was elicited during optical stimulation. The experimental results show that ankle movement can be generated wirelessly using optical stimulation pulse parameters.
Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Authors: Li, Xiaoheng; Wang, Zhao; Jiang, Zhenming; Guo, Jingjing; Zhang, Yuxi; Li, Chenhao; Chung, Jinyong; Folmer, Janet; Liu, June; Lian, Qingquan; Ge, Renshan; Zirkin, Barry R.; Chen, Haolin
Abstract
Testicular Leydig cells are the primary source of testosterone in males. Adult Leydig cells have been shown to arise from stem cells present in the neonatal testis. Once established, adult Leydig cells turn over only slowly during adult life, but when these cells are eliminated experimentally from the adult testis, new Leydig cells rapidly reappear. As in the neonatal testis, stem cells in the adult testis are presumed to be the source of the new Leydig cells. As yet, the mechanisms involved in regulating the proliferation and differentiation of these stem cells remain unknown. We developed a unique in vitro system of cultured seminiferous tubules to assess the ability of factors from the seminiferous tubules to regulate the proliferation of the tubule-associated stem cells, and their subsequent entry into the Leydig cell lineage. The proliferation of the stem Leydig cells was stimulated by paracrine factors including Desert hedgehog (DHH), basic fibroblast growth factor (FGF2), platelet-derived growth factor (PDGF), and activin. Suppression of proliferation occurred with transforming growth factor beta (TGF-beta). The differentiation of the stem cells was regulated positively by DHH, lithium-induced signaling, and activin, and negatively by TGF-beta, PDGFBB, and FGF2. DHH functioned as a commitment factor, inducing the transition of stem cells to the progenitor stage and thus into the Leydig cell lineage. Additionally, CD90 (Thy1) was found to be a unique stem cell surface marker that was used to obtain purified stem cells by flow cytometry.