Involvement of mesenchymal stem cells in cancer progression and metastases.

Mesenchymal stem/stromal cells (MSCs) are known to be the helpers for the healing of tissue damage, often referred to as ambulatory cells. However, MSCs are also recruited by cancer cells to similarly aid in tumor growth and progression. In this review, some of the key steps in cancer progression and metastases are described including the various steps in which MSCs participate and may play important roles. MSCs aid in cancer cells' ability to evade immune attack, while promoting tumor angiogenesis, even being counter-acting against chemotherapeutics and other drugs used to fight various cancers. Furthermore, MSCs participate in many of the crucial steps in invasion and metastasis, including stimulating the epithelial-mesenchymal transition (EMT) and induction of stem-like properties that allow cancer stem cells to increase their survivability through the circulation. These steps are described in detail. Differences between circulating tumor cells (CTCs) and cancer stem cells (CSCs) are discussed, along with descriptions of the formation of a pre-metastatic niche, the role of exosomes from both cancer cells and MSCs in metastasis and tumor reseeding (self-seeding). More and more, MSCs are being proposed as a promising tumor targeting drug-delivery tool. In order to fulfill this promise, further understanding of the precise roles that MSCs play in the process of cancer metastases must be achieved, in attempting to create remedies that will improve the outcome of available therapeutics.

Human COL7A1-corrected induced pluripotent stem cells for the treatment of recessive dystrophic epidermolysis bullosa.

Patients with recessive dystrophic epidermolysis bullosa (RDEB) lack functional type VII collagen owing to mutations in the gene COL7A1 and suffer severe blistering and chronic wounds that ultimately lead to infection and development of lethal squamous cell carcinoma. The discovery of induced pluripotent stem cells (iPSCs) and the ability to edit the genome bring the possibility to provide definitive genetic therapy through corrected autologous tissues. We generated patient-derived COL7A1-corrected epithelial keratinocyte sheets for autologous grafting. We demonstrate the utility of sequential reprogramming and adenovirus-associated viral genome editing to generate corrected iPSC banks. iPSC-derived keratinocytes were produced with minimal heterogeneity, and these cells secreted wild-type type VII collagen, resulting in stratified epidermis in vitro in organotypic cultures and in vivo in mice. Sequencing of corrected cell lines before tissue formation revealed heterogeneity of cancer-predisposing mutations, allowing us to select COL7A1-corrected banks with minimal mutational burden for downstream epidermis production. Our results provide a clinical platform to use iPSCs in the treatment of debilitating genodermatoses, such as RDEB.