Congenital limb deficiency: Genetic investigation of 44 individuals presenting mainly longitudinal defects in isolated or syndromic forms.

Congenital limb deficiency (CLD), one of the most common congenital anomalies, is characterized by hypoplasia/aplasia of one or more limb bones and can be isolated or syndromic. The etiology in CLD is heterogeneous, including environmental and genetic factors. A fraction remains with no etiological factor identified. We report the study of 44 Brazilian individuals presenting isolated or syndromic CLD, mainly with longitudinal defects. Genetic investigation included particularly next-generation sequencing (NGS) and/or chromosomal microarray. The overall diagnostic yield was 45.7%, ranging from 60.9% in the syndromic to 16.7% in the non-syndromic group. In TAR syndrome, a common variant in 3´UTR of RBM8A, in trans with 1q21.1 microdeletion, was detected, corroborating the importance of this recently reported variant in individuals of African ancestry. NGS established a diagnosis in three individuals in syndromes recently reported or still under delineation (an acrofacial dysostosis, Coats plus and Verheij syndromes), suggesting a broader phenotypic spectrum in these disorders. Although a low rate of molecular detection in non-syndromic forms was observed, it is still possible that variants in non-coding regions and small CNVs, not detected by the techniques applied in this study, could play a role in the etiology of CLD.

Immunocompetent Brain Organoids with Microglia Allow Advanced Aging Research.

Aging is a complex and multifactorial process that significantly affects brain function and health, since it is commonly associated with the emergence of neurodegenerative diseases. Recent advances in stem cell technology have facilitated the development of brain organoids, three-dimensional structures that mimic key aspects of brain architecture and functionality. By incorporating microglia, the resident monocyte-derived immune cells of the central nervous system, immunocompetent brain organoids can provide a more physiologically relevant model for studying brain aging. This chapter explores the methodology of immunocompetent brain organoids for advanced aging research, detailing protocols for their generation from a co-culture of neural stem cells and primitive macrophage progenitors.

Clinical Application of Human Induced Pluripotent Stem Cell-Derived Organoids as an Alternative to Organ Transplantation.

Transplantation is essential and crucial for individuals suffering from end-stage organ failure diseases. However, there are still many challenges regarding these procedures, such as high rates of organ rejection, shortage of organ donors, and long waiting lines. Thus, investments and efforts to develop laboratory-grown organs have increased over the past years, and with the recent progress in regenerative medicine, growing organs in vitro might be a reality within the next decades. One of the many different strategies to address this issue relies on organoid technology, a miniaturized and simplified version of an organ. Here, we address recent progress on organoid research, focusing on transplantation of intestine, retina, kidney, liver, pancreas, brain, lung, and heart organoids. Also, we discuss the main outcomes after organoid transplantation, common challenges faced by these promising regenerative medicine approaches, and future perspectives on the field.