The Impact of Tumor Necrosis Factor on Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells In Vitro

Chronic inflammatory diseases are characterized by elevated levels of tumor necrosis factor (TNF) and decreasing bone mineral density. TNF promotes differentiation of bone resorbing osteoclasts from their hematopoietic precursors. Its impact on differentiation of mesenchymal precursors of bone forming osteoblasts isolated from adipose (ASC) was largely unknown. I found that TNF did neither induce osteoblastic differentiation of ASC nor exhibited an impact on osteoblastic differentiation in vitro. Thus, TNF mediates osteolysis in vivo presumably mainly by its pro-osteoclastogenic effect

Gelatin-based hydrogels promote chondrogenic differentiation of human adipose tissue-derived mesenchymal stem cells in vitro

Due to the weak regeneration potential of cartilage, there is a high clinical incidence of articular joint disease, leading to a strong demand for cartilaginous tissue surrogates. The aim of this study was to evaluate a gelatin-based hydrogel for its suitability to support chondrogenic differentiation of human mesenchymal stem cells. Gelatin-based hydrogels are biodegradable, show high biocompatibility, and offer possibilities to introduce functional groups and/or ligands. In order to prove their chondrogenesis-supporting potential, a hydrogel film was developed and compared with standard cell culture polystyrene regarding the differentiation behavior of human mesenchymal stem cells. Cellular basis for this study were human adipose tissue-derived mesenchymal stem cells, which exhibit differentiation potential along the adipogenic, osteogenic and chondrogenic lineage. The results obtained show a promotive effect of gelatin-based hydrogels on chondrogenic differentiation of mesenchymal stem cells in vitro and therefore encourage subsequent in vivo studies

HIV and COVID-19: two pandemics with significant (but different) central nervous system complications

Human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause significant neurologic disease. Central nervous system (CNS) involvement of HIV has been extensively studied, with well-documented invasion of HIV into the brain in the initial stage of infection, while the acute effects of SARS-CoV-2 in the brain are unclear. Neuropathologic features of active HIV infection in the brain are well characterized whereas neuropathologic findings in acute COVID-19 are largely non-specific. On the other hand, neuropathologic substrates of chronic dysfunction in both infections, as HIV-associated neurocognitive disorders (HAND) and post-COVID conditions (PCC)/long COVID are unknown. Thus far, neuropathologic studies on patients with HAND in the era of combined antiretroviral therapy have been inconclusive, and autopsy studies on patients diagnosed with PCC have yet to be published. Further longitudinal, multidisciplinary studies on patients with HAND and PCC and neuropathologic studies in comparison to controls are warranted to help elucidate the mechanisms of CNS dysfunction in both conditions

Photo-crosslinkable biopolymer hydrogels for targeted tissue engineering

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Photo-crosslinkable biopolymers targeting stem cell adhesion and proliferation: the case study of gelatin and starch-based IPNs

The present work focuses on the development of biomaterials that support the adhesion and the proliferation of adipose-tissue derived stem cells. Therefore, gelatin and starch are selected as starting materials. Both hydrogel building blocks are of great interest as they provide a general chemical structure comparable to the protein and the polysaccharide constituting part of the extracellular matrix. Crosslinkable side groups are incorporated on both biopolymers to enable the subsequent chemical crosslinking, thereby ensuring their stability at physiological temperature. An in vitro cellular assay revealed that the hydrogels developed are biocompatible and supported cell adhesion of adipose-tissue derived mesenchymal stem cells. The presence of the starch phase tempered the adhesion resulting in local cell detachment. The results thus indicate that by carefully varying the ratio of the two building blocks, hydrogels can be developed possessing a controllable cell adhesion behavior