Increased Expression of Cell Surface SSEA-1 is Closely Associated with Naïve-Like Conversion from Human Deciduous Teeth Dental Pulp Cells-Derived iPS Cells

Exploring SSEA3 as an emerging biomarker for assessing the regenerative potential of dental pulp-derived stem cells

Background

Human dental pulp-derived stem cells (hDPSCs) have emerged as a promising source for adult stem cell-based regenerative medicine. Stage-specific embryonic antigen 3 (SSEA3) is a cell surface marker associated with Multilineage-differentiating stress-enduring (Muse) cells, a subpopulation of human bone marrow-derived stem cells (hBMSCs), known for their potent regenerative potential and safety profile. In this study, we investigated the influence of the prolonged culture period and the number of culture passages on the regenerative capacity of hDPSCs and explored the association between SSEA3 expression and their regenerative abilities.

Methods

hDPSCs were isolated and cultured for up to 20 passages. Cell proliferation, migration, and osteogenic, adipogenic and neurogenic differentiation potential were assessed at passages 5, 10, and 20. Flow cytometry and immunofluorescence were employed to analyze SSEA3 expression. RNA sequencing (RNA-seq) was performed on SSEA3-positive and SSEA3-negative hDPSCs to identify differentially expressed genes and associated pathways.

Results

Our findings demonstrated a progressive decline in hDPSCs proliferation and migration capacity with increasing passage number. Conversely, cell size exhibited a positive correlation with passage number. Early passage hDPSCs displayed superior osteogenic and adipogenic differentiation potential. Notably, SSEA3 expression exhibited a significant negative correlation with passage numbers, reflecting the observed decline in differentiation capacity. RNA-seq analysis revealed distinct transcriptional profiles between SSEA3-positive and SSEA3-negative hDPSCs. SSEA3-positive cells displayed upregulation of genes associated with ectodermal differentiation and downregulation of genes involved in cell adhesion.

Conclusions

This study elucidates the impact of passaging on hDPSC behavior and suggests SSEA3 as a valuable biomarker for evaluating stemness and regenerative potential. SSEA3-positive hDPSCs, functionally analogous to Muse cells, represent a promising cell population for developing targeted regenerative therapies with potentially improved clinical outcomes.

Gene-repaired iPS cells as novel approach for patient with osteogenesis imperfecta

Introduction: The benefits of patient's specific cell/gene therapy have been reported in relation to numerous genetic related disorders including osteogenesis imperfecta (OI). In osteogenesis imperfecta particularly also a drug therapy based on the administration of bisphosphonates partially helped to ease the symptoms. Methods: In this controlled trial, fibroblasts derived from patient diagnosed with OI type II have been successfully reprogrammed into induced Pluripotent Stem cells (iPSCs) using Yamanaka factors. Those cells were subjected to repair mutations found in the COL1A1 gene using homologous recombination (HR) approach facilitated with star polymer (STAR) as a carrier of the genetic material. Results: Delivery of the correct linear DNA fragment to the osteogenesis imperfecta patient's cells resulted in the repair of the DNA mutation with an 84% success rate. IPSCs showed 87% viability after STAR treatment and 82% with its polyplex. Discussion: The use of novel polymer Poly[N,N-Dimethylaminoethyl Methacrylate-co-Hydroxyl-Bearing Oligo(Ethylene Glycol) Methacrylate] Arms (P(DMAEMA-co-OEGMA-OH) with star-like structure has been shown as an efficient tool for nucleic acids delivery into cells (Funded by National Science Centre, Contract No. UMO-2020/37/N/NZ2/01125).

In vitro induced pluripotency from urine-derived cells in porcine

BACKGROUND

The generation of induced pluripotent stem cells (iPSC) has been a game-changer in translational and regenerative medicine; however, their large-scale applicability is still hampered by the scarcity of accessible, safe, and reproducible protocols. The porcine model is a large biomedical model that enables translational applications, including gene editing, long term in vivo and offspring analysis; therefore, suitable for both medicine and animal production.

AIM

To reprogramme in vitro into pluripotency, and herein urine-derived cells (UDCs) were isolated from porcine urine.

METHODS

The UDCs were reprogrammed in vitro using human or murine octamer-binding transcription factor 4 (OCT4), SRY-box2 (SOX2), Kruppel-like factor 4 (KLF4), and C-MYC, and cultured with basic fibroblast growth factor (bFGF) supplementation. To characterize the putative porcine iPSCs three clonal lineages were submitted to immunocytochemistry for alkaline phosphatase (AP), OCT4, SOX2, NANOG, TRA1 81 and SSEA 1 detection. Endogenous transcripts related to the pluripotency (OCT4, SOX2 and NANOG) were analyzed via reverse transcription quantitative real-time polymerase chain reaction in different time points during the culture, and all three lineages formed embryoid bodies (EBs) when cultured in suspension without bFGF supplementation.

RESULTS

The UDCs were isolated from swine urine samples and when at passage 2 submitted to in vitro reprogramming. Colonies of putative iPSCs were obtained only from UDCs transduced with the murine factors (mOSKM), but not from human factors (hOSKM). Three clonal lineages were isolated and further cultured for at least 28 passages, all the lineages were positive for AP detection, the OCT4, SOX2, NANOG markers, albeit the immunocytochemical analysis also revealed heterogeneous phenotypic profiles among lineages and passages for NANOG and SSEA1, similar results were observed in the abundance of the endogenous transcripts related to pluripotent state. All the clonal lineages when cultured in suspension without bFGF were able to form EBs expressing ectoderm and mesoderm layers transcripts.

CONCLUSION

For the first time UDCs were isolated in the swine model and reprogrammed into a pluripotent-like state, enabling new numerous applications in both human or veterinary regenerative medicine.

Sinking Our Teeth in Getting Dental Stem Cells to Clinics for Bone Regeneration

Dental stem cells have been isolated from the medical waste of various dental tissues. They have been characterized by numerous markers, which are evaluated herein and differentiated into multiple cell types. They can also be used to generate cell lines and iPSCs for long-term in vitro research. Methods for utilizing these stem cells including cellular systems such as organoids or cell sheets, cell-free systems such as exosomes, and scaffold-based approaches with and without drug release concepts are reported in this review and presented with new pictures for clarification. These in vitro applications can be deployed in disease modeling and subsequent pharmaceutical research and also pave the way for tissue regeneration. The main focus herein is on the potential of dental stem cells for hard tissue regeneration, especially bone, by evaluating their potential for osteogenesis and angiogenesis, and the regulation of these two processes by growth factors and environmental stimulators. Current in vitro and in vivo publications show numerous benefits of using dental stem cells for research purposes and hard tissue regeneration. However, only a few clinical trials currently exist. The goal of this review is to pinpoint this imbalance and encourage scientists to pick up this research and proceed one step further to translation.

RNA analysis based on a small number of manually isolated fixed cells (RNA-snMIFxC) to profile stem cells from human deciduous tooth-derived dental pulp cells

Background

Expression of stemness factors, such as octamer-binding transcription factor 3/4 (OCT3/4), sex determining region Y-box 2 (SOX2), and alkaline phosphatase (ALP) in human deciduous tooth-derived dental pulp cells (HDDPCs) can be assessed through fixation and subsequent immuno- or cytochemical staining. Fluorescence-activated cell sorting (FACS), a powerful system to collect cells of interest, is limited by the instrument cost and difficulty in handling. Magnetic-activated cell sorting is inexpensive compared to FACS, but is confined to cells with surface expression of the target molecule. In this study, a simple and inexpensive method was developed for the molecular analysis of immuno- or cytochemically stained cells with intracellular expression of a target molecule, through isolation of a few cells under a dissecting microscope using a mouthpiece-controlled micropipette.

Results

Two or more colored cells (~ 10), after staining with a chromogen such a 3,3′-diaminobenzidine, were successfully segregated from unstained cells. Expression of glyceraldehyde 3-phosphate dehydrogenase, a housekeeping gene, was discernible in all samples, while the expression of stemness genes (such as OCT3/4, SOX2, and ALP) was confined to positively stained cells.

Conclusion

These findings indicate the fidelity of these approaches in profiling cells exhibiting cytoplasmic or nuclear localization of stemness-specific gene products at a small-scale.

Induced Tissue-Specific Stem Cells (iTSCs): Their Generation and Possible Use in Regenerative Medicine

Induced tissue-specific stem cells (iTSCs) are partially reprogrammed cells which have an intermediate state, such as progenitors or stem cells. They originate from the de-differentiation of differentiated somatic cells into pluripotent stem cells, such as induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs), or from the differentiation of undifferentiated cells. They show a limited capacity to differentiate and a morphology similar to that of somatic cell stem cells present in tissues, but distinct from that of iPSCs and ESCs. iTSCs can be generally obtained 7 to 10 days after reprogramming of somatic cells with Yamanaka’s factors, and their fibroblast-like morphology remains unaltered. iTSCs can also be obtained directly from iPSCs cultured under conditions allowing cellular differentiation. In this case, to effectively induce iTSCs, additional treatment is required, as exemplified by the conversion of iPSCs into naïve iPSCs. iTSCs can proliferate continuously in vitro, but when transplanted into immunocompromised mice, they fail to generate solid tumors (teratomas), implying loss of tumorigenic potential. The low tendency of iTSCs to elicit tumors is beneficial, especially considering applications for regenerative medicine in humans. Several iTSC types have been identified, including iTS-L, iTS-P, and iTS-D, obtained by reprogramming hepatocytes, pancreatic cells, and deciduous tooth-derived dental pulp cells, respectively. This review provides a brief overview of iPSCs and discusses recent advances in the establishment of iTSCs and their possible applications in regenerative medicine.

Dental Pulp Stem Cells on Implant Surface: An In Vitro Study

In the field of biology and medicine, one hears often about stem cells and their potential. The dental implant new surfaces, subjected to specific treatments, perform better and allow for quicker healing times and better clinical performance. The purpose of this study is to evaluate from a biological point of view the interaction and cytotoxicity between stem cells derived from dental pulp (DPSCs) and titanium surfaces. Through the creation of complex cells/implant, this study is aimed at analyzing the cytotoxicity of dental implant surfaces (Myth (Maipek Manufacturer Industrial Care, Naples, Italy)) and the adhesion capacity of cells on them and at considering the essential factors for implant healing such as osteoinduction and vasculogenesis. These parameters are pointed out through histology (3D cell culture), immunofluorescence, proliferation assays, scanning electron microscopy, and PCR investigations. The results of the dental implant surface and its interaction with the DPSCs are encouraging, obtaining results increasing the mineralization of the tissues. The knowledge of this type of interaction, highlighting its chemical and biological features, is certainly also an excellent starting point for the development of even more performing surfaces for having better healing in the oral surgical procedures related to dental implant positioning.

Asymptomatic neurotoxicity of amyloid β-peptides (Aβ1-42 and Aβ25-35) on mouse embryonic stem cell-derived neural cells

One of the strategies in the establishment of in vitro oxidative stress models for neurodegenerative diseases, such as Alzheimer's disease (AD), is to induce neurotoxicity by amyloid beta (Aβ) peptides in suitable neural cells. Presently, data on the neurotoxicity of Aβ in neural cells differentiated from stem cells are limited. In this study, we attempted to induce oxidative stress in transgenic 46C mouse embryonic stem cell-derived neurons via treatment with Aβ peptides (Aβ1-42 and Aβ25-35). 46C neural cells were generated by promoting the formation of multicellular aggregates, embryoid bodies in the absence of leukemia inhibitory factor, followed by the addition of all-trans retinoic acid as the neural inducer. Mature neuronal cells were exposed to different concentrations of Aβ1-42 and Aβ25-35 for 24 h. Morphological changes, cell viability, and intracellular reactive oxygen species (ROS) production were assessed. We found that 100 µM Aβ1-42 and 50 µM Aβ25-35 only promoted 40% and 10%, respectively, of cell injury and death in the 46C-derived neuronal cells. Interestingly, treatment with each of the Aβ peptides resulted in a significant increase of intracellular ROS activity, as compared to untreated neurons. These findings indicate the potential of using neurons derived from stem cells and Aβ peptides in generating oxidative stress for the establishment of an in vitro AD model that could be useful for drug screening and natural product studies.

B3GALT5 knockout alters gycosphingolipid profile and facilitates transition to human naïve pluripotency

These studies provide systematically characterized glycosphingolipid (GSL) profiles and expression level of glycosyltransferase upon the conversion of human ESCs from primed to naïve state. We identify a switch of GSL profile from globo- and lacto-series to neolacto-series GSLs, accompanied by the downregulation of β-1,3-galactosyltransferase (B3GALT5) during the pluripotency transition. The CRISPR/Cas9-generated B3GALT5 knockout increases the level of intracellular Ca²⁺, resulting in an intermediate state of pluripotency, which facilitates the primed- to naïve-state transition in human ESCs. In addition, the altered GSL could be rescued through overexpression of B3GALT5. Thus, our results provide a new perspective in the understanding of human pluripotency transition from primed to naïve state, which can be facilitated by changing the expression of single glycosyltransferase, B3GALT5.

Conversion of human pluripotent stem cells from primed to naïve state is accompanied by altered transcriptome and methylome, but glycosphingolipid (GSL) profiles in naïve human embryonic stem cells (hESCs) have not been systematically characterized. Here we showed a switch from globo-(SSEA-3, SSEA-4, and Globo H) and lacto-series (fucosyl-Lc4Cer) to neolacto-series GSLs (SSEA-1 and H type 2 antigen), along with marked down-regulation of β-1,3-galactosyltransferase (B3GALT5) upon conversion to naïve state. CRISPR/Cas9-generated B3GALT5-knockout (KO) hESCs displayed an altered GSL profile, increased cloning efficiency and intracellular Ca²⁺, reminiscent of the naïve state, while retaining differentiation ability. The altered GSLs could be rescued through overexpression of B3GALT5. B3GALT5-KO cells cultured with 2iLAF exhibited naïve-like transcriptome, global DNA hypomethylation, and X-chromosome reactivation. In addition, B3GALT5-KO rendered hESCs more resistant to calcium chelator in blocking entry into naïve state. Thus, loss of B3GALT5 induces a distinctive state of hESCs displaying unique GSL profiling with expression of neolacto-glycans, increased Ca²⁺, and conducive for transition to naïve pluripotency.

Drug-Induced Naïve iPS Cells Exhibit Better Performance than Primed iPS Cells with Respect to the Ability to Differentiate into Pancreatic β-Cell Lineage

Pluripotent stem cells are classified as naïve and primed cells, based on their in vitro growth characteristics and potential to differentiate into various types of cells. Human-induced pluripotent stem cells (iPSCs, also known as epiblast stem cells [EpiSCs]) have limited capacity to differentiate and are slightly more differentiated than naïve stem cells (NSCs). Although there are several in vitro protocols that allow iPSCs to differentiate into pancreatic lineage, data concerning generation of β-cells from these iPSCs are limited. Based on the pluripotentiality of NSCs, it was hypothesized that NSCs can differentiate into pancreatic β-cells when placed under an appropriate differentiation induction condition. We examined whether NSCs can be efficiently induced to form potentially pancreatic β cells after being subjected to an in vitro protocol. Several colonies resembling in vitro-produced β-cell foci, with β-cell-specific marker expression, were observed when NSC-derived embryoid bodies (EBs) were induced to differentiate into β-cell lineage. Conversely, EpiSC-derived EBs failed to form such foci in vitro. Intrapancreatic grafting of the in vitro-formed β-cell foci into nude mice (BALB/c-nu/nu) generated a cell mass containing insulin-producing cells (IPCs), without noticeable tumorigenesis. These NSCs can be used as a promising resource for curing type 1 diabetes.