Nanoparticles Made from iPS Cell-Derived Mesenchymal Stem Cells as Standardized Natural Platforms for Targeted Treatment of Drug-Resistant Prostate Cancer
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Background: Treatment of most metastatic prostate cancers (PCa) relies on chemotherapy, but advanced metastatic PCa develops resistance to current chemotherapy drugs frequently and rapidly. Nanoparticles are promising platforms to overcome such drug resistance, but the accumulation of mainstream passively tumor-targeting nanoparticles in tumors is limited. Nanoghosts (NGs) are novel, actively tumor-targeting nanoparticles made from cytoplasmic membranes (ghost cells) of bone marrow (BM) mesenchymal stem cell (MSC) and showed superior capacity of delivering an anti-cancer protein via intraperitoneal (IP) injection than liposome in a mouse PCa model. However, a huge amount of MSCs is needed to prepare enough NGs for such therapy even in mice. A similar but simpler method was used to produce nanovesicles (NVs) containing cytoplasmic components from macrophages with much higher efficiency and showed superior efficacy of delivering chemotherapy drugs via intravenously (IV) injection than liposome in a mouse colon cancer model by targeting inflamed endothelial cells in tumors, but the pro-tumor activities of cytoplasmic components of tissue-derived MSCs impede the research of NVs made from MSCs. For further research in large-animal models and future clinical trials of MSC NGs/NVs in cancer therapy, a huge amount of standardized MSCs will be needed. Tissue-derived MSCs have limited expandability, considerable donor variations, and significant decrease of tumor targeting capacity after prolonged expansion; hence, they cannot serve as a reliable source for NGs/NVs. My laboratory derived MSCs from a human induced pluripotent stem cell (iPSC) line with almost unlimited expandability using an improved protocol that can be readily scaled up to produce an enormous amount of standardized MSCs with consistent tumor targeting capacity. Moreover, the expression of many cytoplasmic pro-tumor factors in our iPSC-MSCs is remarkably lower than that in BM-MSCs. We prepared both NGs and NVs from iPSC-MSCs with a threefold higher yield of NVs than that of NGs. The in vitro selective binding to PCa cells of both NVs and NGs was confirmed in tests with a wide range of particle concentrations and incubation periods, and the PCa selectivity of NVs is always higher than that of NGs. Another issue of BM-MSC NGs is that their PCa-targeted biodistribution via the IV route is much less and not sustainable in comparison to IP route; hence, they appear not ideal to deliver chemotherapy drugs for tumors outside of the peritoneal cavity due to the worry on inflammation and respiratory muscle weakness caused by these drugs via IP route. Genetic engineering to express additional molecules targeting inflamed tumor endothelial cells to enhance vascular permeability on MSC membranes is promising to enhance the selective accumulation of IV infused NGs/NVs in PCa. Safe genetic engineering has been achieved in immortal iPSCs by inserting transgenes into safe harbor locus, but is impractical in tissue-derived MSCs due to the requirement of prolonged culture for clone selection.Hypothesis: Based on our preliminary data, I hypothesize that nanoparticles reconstructed from our iPSC-MSCs, i.e., NGs/NVs, will improve treatment of drug-resistant PCa by providing a standardized natural targeting platform with unlimited and reliable supply, increased safety, and ease of safe genetic engineering.Specific Aims: (1) Evaluate the real-time biodistribution and PCa targeting capacity of iPSC-MSC NGs/NVs. (2) Determine whether the selective accumulation of iPSC-MSC NGs/NVs in PCa can be improved by carrying additional molecules targeting both PCa and inflamed endothelial cells. (3) Examine whether iPSC-MSC NGs/NVs loaded with anti-PCa agents can improve the targeted delivery of these agents into metastatic PCa.Study Design: (1) Make NGs and NVs from iPSC-MSCs transduced with a membrane-bound Metridia luciferase (MetLuc-Mem), then examine the real-time biodistribution and tumor-targeting capacity of IP or IV infused NGs/NVs in mice carrying subcutaneous or bone metastatic PC3 PCa tumors with in vivo bioluminescence imaging. (2) Engineer iPSC-MSCs to express peptides targeting Integrin alphavbeta3 and/or Neuropilin-1 that are highly expressed in PCa cells and inflamed endothelial cells. These peptides will be fused to a protein successfully used to display fused short peptide sequences at high levels on the surface of live transfected cells. The PCa-targeting capability and biodistribution of these NVs/NGs will be compared as in Aim 1. (3) If the accumulation of certain NGs/NVs in PCa after IV injection is significantly increased in Aim 2, we will load them with doxorubicin, and then examine their effects and doxorubicin distribution after IV infusion in comparison with free or liposomal doxorubicin. Otherwise, we will engineer iPSC-MSCs to express membrane-bound TRAIL, an anti-PCa protein, prepare NGs/NVs carrying membrane-bound TRAIL, and examine their effects in vitro and in vivo after IP infusion in comparison with free or liposomal soluble TRAIL.Impact: The success of proposed work will provide the proof of concept of using iPSC-MSCs NGs or NVs as a standardized natural PCa-targeting platform for delivering anti-PCa agents to improve the treatment of drug-resistant metastatic PCa.
