No abstract

Stem cells at the limbus mediate corneal epithelial regeneration and regulate normal tissue homeostasis. Ex vivo cultured limbal epithelial transplantations are being widely practiced in the treatment of limbal stem cell deficiency. In this report, we examined whether the limbal niche cells that nurture and regulate epithelial stem cells coexist in ex vivo limbal cultures. We also compared the inherent differences between explant and suspension culture systems in terms of spatial distribution of niche cells and their effect on epithelial stem cell proliferation, migration, and differentiation in vitro. We report that the stem cell content of both culture systems was similar, explaining the comparable clinical outcomes reported using these two methods. We also showed that the niche cells get expanded in culture and the nestin-positive cells migrate at the leading edges to direct epithelial cell migration in suspension cultures, whereas they are limited to the intact niche in explant cultures. We provide evidence that C/EBPd-positive, p15-positive, and quiescent, label-retaining, early activated stem cells migrate at the leading edges to regulate epithelial cell proliferation in explant cultures, and this position effect is lost in early suspension cultures. However, in confluent suspension cultures, the stem cells and niche cells interact with each another, migrate in spiraling patterns, and self-organize to form three-dimensional niche-like compartments resembling the limbal crypts and thereby reestablish the position effect. These 3D-sphere clusters are enriched with nestin-, vimentin-, S100-, and p27-positive niche cells and p15-, p21-, p63a-, C/EBPd-, ABCG2-, and Pax6-positive quiescent epithelial stem cells. STEM CELLS

Corneal injuries are among the leading causes of blindness and vision impairment. Trauma, infectious keratitis, thermal and chemical (acids and alkali burn) injuries may lead to irreversible corneal scarring, neovascularization, conjunctivalization, and limbal stem cell deficiency. Bilateral blindness constitutes 12% of total global blindness and corneal transplantation remains a stand-alone treatment modality for the majority of end-stage corneal diseases. However, global shortage of donor corneas, the potential risk of graft rejection, and severe side effects arising from long-term use of immunosuppressive medications, demands alternative therapeutic approaches. Umbilical cord-derived mesenchymal stem cells can be isolated in large numbers using a relatively less invasive procedure. However, their role in injury induced corneal repair is largely unexplored. Here, we isolated, cultured and characterized mesenchymal stem cells from human umbilical cord, and studied the expression of mesenchymal (CD73, CD90, CD105, and CD34), ocular surface and epithelial (PAX6, WNT7A, and CK-8/18) lineage markers through immunofluorescence. The cultured human limbal and corneal epithelial cells were used as controls. Scratch assay was used to study the corneal epithelial repair potential of umbilical cord-derived mesenchymal stem cells, in vitro. The in vitro cultured umbilical cord-derived mesenchymal stem cells were plastic adherent, showed trilineage differentiation and expressed: mesenchymal markers CD90, CD105, CD73; epithelial marker CK-8/18, and ocular lineage developmental markers PAX6 and WNT-7A. Our findings suggest that umbilical cord-derived mesenchymal stem cells promote repair of the injured corneal epithelium by stimulating the proliferation of corneal epithelial cells, in vitro. They may serve as a potential non-ocular source of stem cells for treating injury induced bilateral corneal diseases.

Osteosarcoma is an aggressive bone cancer found in children and adolescents. The combined treatment strategy includes the surgical removal of tumour and subsequent chemotherapy to prevent the reoccurrence has been a widely accepted approach. However, the drug resistance developed by tumour cells causes recurrence of cancer. It is imperative to understand the molecular mechanism involved in the development of drug resistance and tumour progression for developing potential therapy. Tumour microenvironment and cellular cross-talk via activation of various signalling pathways are responsible for tumour progression and metastasis. The comprehensive reviews are already available on the tumour microenvironment, signalling cascades responsible for tumour progression, and cellular crosstalk between malignant cells and immune cells. Therefore, we intend to provide comprehend review postulating the importance of mesenchymal stem cells (MSCs) in osteosarcoma progression and metastasis. This paper is aimed to provide information sequentially includes: tumour microenvironment, MSCs role in osteosarcoma progression, the hypoxic environment in MSCs recruitment at the tumour site and the importance of exosomes in tumorigenesis, progression and metastasis. Overall, this review may enlighten the research on the role of MSCs and MSCs derived exosome in osteosarcoma progression and drug resistance. This possibly may result in developing novel therapeutic approaches to combat the osteosarcoma effectively and contributes for the development of prognosis tools for early diagnosis.