Stem cells strike back: advancements in Alzheimer's and Parkinson's disease treatment and modeling efforts from 2019 to 2024.

This review critically evaluates the current state of stem cell therapy (SCT) for treating and modeling of Alzheimer's (AD) and Parkinson's disease (PD). It includes an in-depth analysis of both preclinical and clinical studies, with a particular focus on clinical trials conducted between 2019 and 2024, reflecting recent advancements in the field. Preclinical studies were examined to elucidate the molecular mechanisms underlying SCT and identify developments that could be translated into clinical practice. Within these studies, stem cells, including embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), neural stem cells (NSCs), and induced pluripotent stem cells (iPSCs), have shown high differentiation and proliferation abilities. These properties, along with their capacity to inhibit inflammation, prevent apoptosis, and stimulate angiogenesis, make them promising candidates for treating AD and PD. Over the past 15 years, 76 SCT-based trials have been conducted-27 for AD and 48 for PD-with more than half occurring in the past 5 years. Despite the promise of SCT, the field faces challenges such as ethical concerns regarding the use of ESCs, heterogeneity of isolated cultures, and inconsistent results across preclinical trials. Novel materials and electromagnetic fields (EMFs) offer potential solutions to these issues. While bioengineering approaches can enhance the successful engraftment of transplanted stem cells, EMFs can direct the cells' migration and differentiation. In conclusion, although significant progress has been made in SCT, ongoing efforts are needed to address existing challenges. Nevertheless, SCT holds considerable promise for the future, offering potential breakthroughs in the treatment of neurodegenerative diseases.