Scaling-Up of Dental Pulp Stem Cells Isolated from Multiple Niches

Dental pulp (DP) can be extracted from child’s primary teeth (deciduous), whose loss occurs spontaneously by about 5 to 12 years. Thus, DP presents an easy accessible source of stem cells without ethical concerns. Substantial quantities of stem cells of an excellent quality and at early (2–5) passages are necessary for clinical use, which currently is a problem for use of adult stem cells. Herein, DPs were cultured generating stem cells at least during six months through multiple mechanical transfers into a new culture dish every 3–4 days. We compared stem cells isolated from the same DP before (early population, EP) and six months after several mechanical transfers (late population, LP). No changes, in both EP and LP, were observed in morphology, expression of stem cells markers (nestin, vimentin, fibronectin, SH2, SH3 and Oct3/4), chondrogenic and myogenic differentiation potential, even after cryopreservation. Six hours after DP extraction and in vitro plating, rare 5-bromo-2′-deoxyuridine (BrdU) positive cells were observed in pulp central part. After 72 hours, BrdU positive cells increased in number and were found in DP periphery, thus originating a multicellular population of stem cells of high purity. Multiple stem cell niches were identified in different zones of DP, because abundant expression of nestin, vimentin and Oct3/4 proteins was observed, while STRO-1 protein localization was restricted to perivascular niche. Our finding is of importance for the future of stem cell therapies, providing scaling-up of stem cells at early passages with minimum risk of losing their “stemness”

Fibroblast sources: Where can we get them?

Fibroblasts are cells widely used in cell culture, both for transient primary cell culture or permanent as transformed cell lines. Lately, fibroblasts become cell sources for use in disease modeling after cell reprogramming because it is easily accessible in the body. Fibroblasts in patients will maintain all genetic background during reprogramming into induced pluripotent stem cells. In spite of their large use, fibroblasts are obtained after an invasive procedure, a superficial punch skin biopsy, collected under patient's local anesthesia. Taking into consideration the minimum patient's discomfort during and after the biopsy procedure, as well as the aesthetics aspect, it is essential to reflect on the best site of the body for the biopsy procedure combined with the success of getting robust fibroblast cultures in the lab. For this purpose, we compared the efficiency of four biopsy sites of the body (skin from eyelid, back of the ear, abdominal cesarean scar and groin). Cell proliferation assays and viability after cryopreservation were measured. Our results revealed that scar tissue provided fibroblasts with higher proliferative rates. Also, fibroblasts from scar tissues presented a higher viability after the thawing process

A human neurodevelopmental model for Williams syndrome

Williams syndrome (WS) is a genetic neurodevelopmental disorder characterized by an uncommon hypersociability and a mosaic of retained and compromised linguistic and cognitive abilities. Nearly all clinically diagnosed individuals with WS lack precisely the same set of genes, with breakpoints in chromosome band 7q11.23(1–5). The contribution of specific genes to the neuroanatomical and functional alterations, leading to behavioral pathologies in humans, remains largely unexplored. Here, we investigate neural progenitor cells (NPCs) and cortical neurons derived from WS and typically developing (TD) induced pluripotent stem cells (iPSCs). WS NPCs have an increased doubling time and apoptosis compared to TD NPCs. Using an atypical WS subject(6, 7), we narrowed this cellular phenotype to a single gene candidate, FZD9. At the neuronal stage, WS-derived layers V/VI cortical neurons were characterized by longer total dendrites, increased numbers of spines and synapses, aberrant calcium oscillation and altered network connectivity. Morphometric alterations observed in WS neurons were validated after Golgi staining of postmortem layers V/VI cortical neurons. This human iPSC model(8) fills in the current knowledge gap in WS cellular biology and could lead to further insights into the molecular mechanism underlying the disorder and the human social brain