Chondrogenic differentiation in vitro of hiPSCs activates pathways engaged in limb development

Ionizing radiation exposure of stem cell-derived chondrocytes affects their gene and microRNA expression profiles and cytokine production

Human induced pluripotent stem cells (hiPSCs) can be differentiated into chondrocyte-like cells. However, implantation of these cells is not without risk given that those transplanted cells may one day undergo ionizing radiation (IR) in patients who develop cancer. We aimed to evaluate the effect of IR on chondrocyte-like cells differentiated from hiPSCs by determining their gene and microRNA expression profile and proteomic analysis. Chondrocyte-like cells differentiated from hiPSCs were placed in a purpose-designed phantom to model laryngeal cancer and irradiated with 1, 2, or 3 Gy. High-throughput analyses were performed to determine the gene and microRNA expression profile based on microarrays. The composition of the medium was also analyzed. The following essential biological processes were activated in these hiPSC-derived chondrocytes after IR: "apoptotic process", "cellular response to DNA damage stimulus", and "regulation of programmed cell death". These findings show the microRNAs that are primarily responsible for controlling the genes of the biological processes described above. We also detected changes in the secretion level of specific cytokines. This study demonstrates that IR activates DNA damage response mechanisms in differentiated cells and that the level of activation is a function of the radiation dose.

Paracrine Interactions Involved in Human Induced Pluripotent Stem Cells Differentiation into Chondrocytes

Osteoarthritis (OA), as a degenerative joint disease, is the most common form of joint disorder that causes pain, stiffness, and other symptoms associated with OA. Various genetic, biomechanical, and environmental factors have a relevant role in the development of OA. To date, extensive efforts are currently being made to overcome the poor self-healing capacity of articular cartilage. Despite the pivotal role of chondrocytes, their proliferation and repair capacity after tissue injury are limited. Therefore, the development of new strategies to overcome these constraints is urgently needed. Recent advances in regenerative medicine suggest that pluripotent stem cells are promising stem cell sources for cartilage repair. Pluripotent stem cells are undifferentiated cells that have the capacity to differentiate into different types of cells and can self-renew indefinitely. In the past few decades, numerous attempts have been made to regenerate articular cartilage by using induced pluripotent stem cells (iPSCs). The potential applications of patient-specific iPSCs hold great promise for regenerative medicine and OA treatment. However, there are different culture conditions for the preparation and characterization of human iPSCs-derived chondrocytes (hiChondrocytes). Recent biochemical analyses reported that several paracrine factors such as TGFb, BMPs, WNT, Ihh, and Runx have been shown to be involved in cartilage cell proliferation and differentiation from human iPSCs. In this review, we summarize and discuss the paracrine interactions involved in human iPSCs differentiation into chondrocytes in different cell culture media.

Surgical Wound Fluids from Patients with Breast Cancer Reveal Similarities in the Biological Response Induced by Intraoperative Radiation Therapy and the Radiation-Induced Bystander Effect-Transcriptomic Approach

In patients with breast cancer who undergo breast-conserving surgery (BCS), more than 90% of local recurrences occur in the same quadrant as the primary cancer. Surgical wound fluids (SWF) are believed to play a role in this process by inducing an inflammatory process in the scar tissue area. Despite strong clinical data demonstrating the benefits of intraoperative radiotherapy (IORT), the biological basis underlying this process remains poorly understood. Ionizing radiation (IR) directly affects cells by damaging DNA, thereby altering the cell phenotype. IR directly affects cancer cells and also influences unirradiated cells located nearby, a phenomenon known as the radiation-induced bystander effect (RIBE), significantly modifying the tumor microenvironment. We hypothesized that SWF obtained from patients after BCS and IORT would induce a radiobiological response (due to RIBE) in unirradiated cells, thereby modifying their phenotype. To confirm this hypothesis, breast cancer cells were incubated with SWF collected from patients after BCS: (1) without IORT (wound fluid (WF) group), (2) with IORT (radiotherapy wound fluid (RT-WF) group), and (3) WF with conditioned medium from irradiated cells (WF+RIBE group) and then subjected to microarray analysis. We performed gene set enrichment analysis to determine the biological processes present in these cells. This analysis showed that the RT-WF and WF+RIBE groups shared common biological processes, including the enhancement of processes involved in cell-cycle regulation, DNA repair, and oxidative phosphorylation. The WF group was characterized by overrepresentation of pathways involved in the INF-α and INF-γ response, inflammatory response, and the IL6 JAK/STAT3 signaling pathway. These findings show that MDA-MB-468 cells stimulated with surgical wound fluids obtained from patients who underwent BCS plus IORT and from cells stimulated with SWF plus RIBE share common biological processes. This confirms the role of the radiation-induced bystander effect in altering the biological properties of wound fluids.

The Role of MicroRNAs in Early Chondrogenesis of Human Induced Pluripotent Stem Cells (hiPSCs)

Human induced pluripotent stem cells (hiPSCs) play an important role in research regarding regenerative medicine. Particularly, chondrocytes differentiated from hiPSCs seems to be a promising solution for patients suffering from osteoarthritis. We decided to perform chondrogenesis in a three-week monolayer culture. Based on transcriptome analysis, hiPSC-derived chondrocytes (ChiPS) demonstrate the gene expression profile of cells from early chondrogenesis. Chondrogenic progenitors obtained by our group are characterized by significantly high expression of Hox genes, strongly upregulated during limb formation and morphogenesis. There are scanty literature data concerning the role of microRNAs in early chondrogenesis, especially in chondrogenic differentiation of hiPSCs. The main aim of this study was to investigate the microRNA expression profile and to select microRNAs (miRNAs) taking part in early chondrogenesis. Our findings allowed for selection crucial miRNAs engaged in both diminishing pluripotency state and chondrogenic process (inter alia hsa-miR-525-5p, hsa-miR-520c-3p, hsa-miR-628-3p, hsa-miR-196b-star, hsa-miR-629-star, hsa-miR-517b, has-miR-187). These miRNAs regulate early chondrogenic genes such as: HOXD10, HOXA11, RARB, SEMA3C. These results were confirmed by RT-qPCR analysis. This work contributes to a better understanding of the role of miRNAs directly involved in chondrogenic differentiation of hiPSCs. These data may result in the establishment of a more efficient protocol of obtaining chondrocyte-like cells from hiPSCs.