Stem-cell-mediated bone repair has been used in clinical trials for the regeneration of large craniomaxillofacial defects, to slow the process of bone degeneration in patients with osteonecrosis of the femoral head and for prophylactic treatment of distal tibial fractures. Successful regenerative outcomes in these investigations have provided a solid foundation for wider use of stromal cells in skeletal repair therapy. However, employing stromal cells to facilitate or enhance bone repair is far from being adopted into clinical practice. Scientific, technical, practical and regulatory obstacles prevent the widespread therapeutic use of stromal cells. Ironically, one of the major challenges lies in the limited understanding of the mechanisms via which transplanted cells mediate regeneration. Animal models have been used to provide insight, but these models largely fail to reproduce the nuances of human diseases and bone defects. Consequently, the development of targeted approaches to optimize cell-mediated outcomes is difficult. In this Review, we highlight the successes and challenges reported in several clinical trials that involved the use of bone-marrow-derived mesenchymal or adipose-tissue-derived stromal cells. We identify several obstacles blocking the mainstream use of stromal cells to enhance skeletal repair and highlight technological innovations or areas in which novel techniques might be particularly fruitful in continuing to advance the field of skeletal regenerative medicine.

The delivery of curcumin, a broad-spectrum anticancer drug, has been explored in the form of liposomal nanoparticles to treat osteosarcoma (OS). Curcumin is water insoluble and an effective delivery route is through encapsulation in cyclodextrins followed by a second encapsulation in liposomes. Liposomal curcumin’s potential was evaluated against cancer models of mesenchymal (OS) and epithelial origin (breast cancer). The resulting 2-Hydroxypropyl-γ-cyclodextrin/curcumin - liposome complex shows promising anticancer potential both in vitro and in vivo against KHOS OS cell line and MCF-7 breast cancer cell line. An interesting aspect is that liposomal curcumin initiates the caspase cascade that leads to apoptotic cell death in vitro in comparison with DMSO-curcumin induced autophagic cell death. In addition, the efficiency of the liposomal curcumin formulation was confirmed in vivo using a xenograft OS model. Curcumin-loaded γ-cyclodextrin liposomes indicate significant potential as delivery vehicles for the treatment of cancers of different tissue origin. From the Clinical Editor Curcumin-loaded γ-cyclodextrin liposomes were demonstrated in vitro to have significant potential as delivery vehicles for the treatment of cancers of mesenchymal and epithelial origin. Differences between mechanisms of cell death were also evaluated.

BackgroundFat grafting is used to restore breast defects after surgical resection of breast tumors. Supplementing fat grafts with adipose tissue-derived stromal/stem cells (ASCs) is proposed to improve the regenerative/restorative ability of the graft and retention. However, long term safety for ASC grafting in proximity of residual breast cancer cells is unknown. The objective of this study was to determine the impact of human ASCs derived from abdominal lipoaspirates of three donors, on a human breast cancer model that exhibits early metastasis.Methodology/Principal FindingsHuman MDA-MB-231 breast cancer cells represents “triple negative” breast cancer that exhibits early micrometastasis to multiple mouse organs [1]. Human ASCs were derived from abdominal adipose tissue from three healthy female donors. Indirect co-culture of MDA-MB-231 cells with ASCs, as well as direct co-culture demonstrated that ASCs had no effect on MDA-MB-231 growth. Indirect co-culture, and ASC conditioned medium (CM) stimulated migration of MDA-MB-231 cells. ASC/RFP cells from two donors co-injected with MDA-MB-231/GFP cells exhibited a donor effect for stimulation of primary tumor xenografts. Both ASC donors stimulated metastasis. ASC/RFP cells were viable, and integrated with MDA-MB-231/GFP cells in the tumor. Tumors from the co-injection group of one ASC donor exhibited elevated vimentin, matrix metalloproteinase-9 (MMP-9), IL-8, VEGF and microvessel density. The co-injection group exhibited visible metastases to the lung/liver and enlarged spleen not evident in mice injected with MDA-MB-231/GFP alone. Quantitation of the total area of GFP fluorescence and human chromosome 17 DNA in mouse organs, H&E stained paraffin sections and fluorescent microscopy confirmed multi-focal metastases to lung/liver/spleen in the co-injection group without evidence of ASC/RFP cells.ConclusionsHuman ASCs derived from abdominal lipoaspirates of two donors stimulated metastasis of MDA-MB-231 breast tumor xenografts to multiple mouse organs. MDA-MB-231 tumors co-injected with ASCs from one donor exhibited partial EMT, expression of MMP-9, and increased angiogenesis.

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