Intervertebral disc regeneration: Influence of growth factors on differentiation of human mesenchymal stem cells (hMSC)

Introduction: One common cause of disability in modern society is low back pain. The main reason for this pain is the degeneration of the intervertebral disc (IVD), particular of the nucleus pulposus (NP). For an early degeneration stage cell-based therapy would be a minimal invasive method of treatment. Therefore, adequate cells are needed. As the usage of NP cells is limited because of their insufficient amount or vitality, a promising alternative is the application of human mesenchymal stem cells (hMSCs). Objective: To investigate the potential of various growth factors to induce the differentiation of hMSCs into NP cells and thereby to obtain an alternative cell source for the treatment of IVD degeneration. Methods: hMSC-TERT were cultivated three-dimensionally in a hydrogel for 21 days to form NP cells. Cell survival and proliferation were determined using SybrGreen/propidium iodide double staining and the WST-test. To investigate the ability of several growth factors to differentiate hMSCs into NP cells, fluorescence immunostaining of NP-specific marker proteins (e.g. chondroadherin (CHAD) and the recently discovered cytokeratin 19 [1]) was performed. Results: Following the procedure described above, cells are able to maintain their viability and proliferation capacity throughout the cultivation time. By using a previously established immunofluorescence protocol, we could indicate the ability of three different growth factors to differentiate hMSCs into NP-like cells. Conclusion: The expression of several marker proteins in all differentiation experiments indicates the ability of IGF-1, FGF-2 and PDGF-BB to differentiate hMSCs into NP-like cells apart from the usually applied TGF-β3. Furthermore, our findings preclude the application of Cytokeratin 19 as a specific marker protein for NP cells [1]. Further experiments have to be done to find real specific NP marker proteins to indisputable verify the differentiation of hMSCs into NP cells. If so, application of the mentioned three growth factors would possibly be an option to obtain sufficient NP cells for minimal invasive IVD regeneration

A fetal wound healing program after intrauterine bile duct injury may contribute to biliary atresia

Background &amp; Aims: Biliary atresia (BA) is an obstructive cholangiopathy that initially affects the extrahepatic bile ducts (EHBDs) of neonates. The etiology is uncertain, but evidence points to a prenatal cause. Fetal tissues have increased levels of hyaluronic acid (HA), which plays an integral role in fetal wound healing. The objective of this study was to determine whether a program of fetal wound healing is part of the response to fetal EHBD injury. Methods: Mouse, rat, sheep, and human EHBD samples were studied at different developmental time points. Models included a fetal sheep model of prenatal hypoxia, human BA EHBD remnants and liver samples taken at the time of the Kasai procedure, EHBDs isolated from neonatal rats and mice, and spheroids and other models generated from primary neonatal mouse cholangiocytes. Results: A wide layer of high molecular weight HA encircling the lumen was characteristic of the normal perinatal but not adult EHBD. This layer, which was surrounded by collagen, expanded in injured ducts in parallel with extensive peribiliary gland hyperplasia, increased mucus production and elevated serum bilirubin levels. BA EHBD remnants similarly showed increased HA centered around ductular structures compared with age-appropriate controls. High molecular weight HA typical of the fetal/neonatal ducts caused increased cholangiocyte spheroid growth, whereas low molecular weight HA induced abnormal epithelial morphology; low molecular weight HA caused matrix swelling in a bile duct-on-a-chip device. Conclusion: The fetal/neonatal EHBD, including in human EHBD remnants from Kasai surgeries, demonstrated an injury response with prolonged high levels of HA typical of fetal wound healing. The expanded peri-luminal HA layer may swell and lead to elevated bilirubin levels and obstruction of the EHBD. Impact and implications: Biliary atresia is a pediatric cholangiopathy associated with high morbidity and mortality rates; although multiple etiologies have been proposed, the fetal response to bile duct damage is largely unknown. This study explores the fetal pathogenesis after extrahepatic bile duct damage, thereby opening a completely new avenue to study therapeutic targets in the context of biliary atresia.</p