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Efficacious and accessible sources of natural killer (NK) cells would widen their use as immunotherapeutics, particularly for solid cancers. Here, we show that human somatic cells can be directly reprogrammed into NK cells with a CD56brightCD16bright phenotype using pluripotency transcription factors and an optimized reprogramming medium. The directly reprogrammed NK cells have strong innate-adaptive immunomodulatory activity and are highly potent against a wide range of cancer cells, including difficult-to-treat solid cancers and cancer stem cells. Both directly reprogrammed NK cells bearing a cancer-specific chimeric antigen receptor and reprogrammed NK cells in combination with antibodies competent for antibody-dependent cell-mediated cytotoxicity led to selective anticancer effects with augmented potency. The direct reprogramming of human somatic cells into NK cells is amenable to the production of autologous and allogeneic NK cells, and will facilitate the design and testing of cancer immunotherapies and combination therapies.

BackgroundSchwann cells (SCs) are primarily responsible for regeneration and repair of the peripheral nervous system (PNS). Renewable and lineage-restricted SC precursors (SCPs) are considered highly desirable and promising cell sources for the production of SCs and for studies of SC lineage development, but SCPs are extremely limited. Here, we present a novel direct conversion strategy for the generation of human SCPs, capable of differentiating into functional SCs.MethodsEasily accessible human skin fibroblast cells were directly induced into integration-free SCPs using episomal vectors (Oct3/4, Klf4, Sox2, L-Myc, Lin28 and p53 shRNA) under SCP lineage-specific chemically defined medium conditions. Induced SCPs (iSCPs) were further examined for their ability to differentiate into SCs. The identification and functionality of iSCPs and iSCP-differentiated SCs (iSCs) were confirmed according to morphology, lineage-specific markers, neurotropic factor secretion, and/or standard functional assays.ResultsHighly pure, Sox 10-positive of iSCPs (more than 95% purity) were generated from human skin fibroblasts within 3 weeks. Established iSCPs could be propagated in vitro while maintaining their SCP identity. Within 1 week, iSCPs could efficiently differentiate into SCs (more than 95% purity). The iSCs were capable of secreting various neurotrophic factors such as GDNF, NGF, BDNF, and NT-3. The in vitro myelinogenic potential of iSCs was assessed by myelinating cocultures using mouse dorsal root ganglion (DRG) neurons or human induced pluripotent stem cell (iPSC)-derived sensory neurons (HSNs). Furthermore, iSC transplantation promoted sciatic nerve repair and improved behavioral recovery in a mouse model of sciatic nerve crush injury in vivo.ConclusionsWe report a robust method for the generation of human iSCPs/iSCs that might serve as a promising cellular source for various regenerative biomedical research and applications, such as cell therapy and drug discovery, especially for the treatment of PNS injury and disorders.

Small molecules that improve reprogramming, stem cell properties, and regeneration can be widely applied in regenerative medicine. Natural plant extracts represent an abundant and valuable source of bioactive small molecules for drug discovery. Natural products themselves or direct derivatives of them have continued to provide small molecules that have entered clinical trials, such as anticancer and antimicrobial drugs. Here, we tested 3695 extracts from native plants to examine whether they can improve induced pluripotent stem cell (iPSC) generation using genetically homogeneous secondary mouse embryonic fibroblasts (MEFs) harboring doxycycline (dox)-inducible reprograming transgenes. Among the tested extracts, extracts from the fruit and stem of Camellia japonica (CJ) enhanced mouse and human iPSC generation and promoted efficient wound healing in an in vivo mouse wound model. CJ is one of the best-known species of the genus Camellia that belongs to the Theaceae family. Our findings identified the natural plant extracts from the fruit and stem of CJ as novel regulators capable of enhancing cellular reprogramming and wound healing, providing a useful supplement in the development of a more efficient and safer method to produce clinical-grade iPSCs and therapeutics.

Small molecules that improve reprogramming, stem cell properties, and regeneration can be widely applied in regenerative medicine. Natural plant extracts represent an abundant and valuable source of bioactive small molecules for drug discovery. Natural products themselves or direct derivatives of them have continued to provide small molecules that have entered clinical trials, such as anticancer and antimicrobial drugs. Here, we tested 3695 extracts from native plants to examine whether they can improve induced pluripotent stem cell (iPSC) generation using genetically homogeneous secondary mouse embryonic fibroblasts (MEFs) harboring doxycycline (dox)-inducible reprograming transgenes. Among the tested extracts, extracts from the fruit and stem of Camellia japonica (CJ) enhanced mouse and human iPSC generation and promoted efficient wound healing in an in vivo mouse wound model. CJ is one of the best-known species of the genus Camellia that belongs to the Theaceae family. Our findings identified the natural plant extracts from the fruit and stem of CJ as novel regulators capable of enhancing cellular reprogramming and wound healing, providing a useful supplement in the development of a more efficient and safer method to produce clinical-grade iPSCs and therapeutics.