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Engineering toxin-resistant therapeutic stem cells to treat brain tumors
Daniel W Stuckey1, Shawn D Hingtgen, Nihal Karakas
1Molecular Neurotherapy and Imaging Laboratory; Department of Radiology.
Abstract:
Pseudomonas exotoxin (PE) potently blocks protein synthesis by catalyzing the inactivation of elongation factor-2 (EF-2). Targeted PE-cytotoxins have been used as antitumor agents, although their effective clinical translation in solid tumors has been confounded by off-target delivery, systemic toxicity, and short chemotherapeutic half-life. To overcome these limitations, we have created toxin-resistant stem cells by modifying endogenous EF-2, and engineered them to secrete PE-cytotoxins that target specifically expressed (interleukin-13 receptor subunit alpha-2) or overexpressed (epidermal growth factor receptor) in glioblastomas (GBM). Molecular analysis correlated efficacy of PE-targeted cytotoxins with levels of cognate receptor expression, and optical imaging was applied to simultaneously track the kinetics of protein synthesis inhibition and GBM cell viability in vivo. The release of IL13-PE from biodegradable synthetic extracellular matrix (sECM) encapsulated stem cells in a clinically relevant GBM resection model led to increased long-term survival of mice compared to IL13-PE protein infusion. Moreover, multiple patient-derived GBM lines responded to treatment, underscoring its clinical relevance. In sum, integrating stem cell-based engineering, multimodal imaging, and delivery of PE-cytotoxins in a clinically relevant GBM model represents a novel strategy and a potential advancement in GBM therapy.
Insights
Engineered stem cells deliver targeted Pseudomonas exotoxin (PE) to glioblastomas, overcoming limitations of previous therapies. This novel approach shows promise for improved glioblastoma treatment and increased survival rates.
Area of Science:
- Biotechnology
- Oncology
- Cell Therapy
Background:
- Pseudomonas exotoxin (PE) inhibits protein synthesis by inactivating elongation factor-2 (EF-2).
- Targeted PE-cytotoxins show antitumor potential but face challenges like systemic toxicity and short half-life in solid tumors.
- Glioblastomas (GBM) overexpress specific receptors like epidermal growth factor receptor.
Purpose of the Study:
- To engineer toxin-resistant stem cells for targeted delivery of PE-cytotoxins to glioblastomas.
- To overcome limitations of current PE-cytotoxin therapies, including off-target delivery and systemic toxicity.
- To evaluate the efficacy of engineered stem cells secreting PE-cytotoxins targeting GBM-specific receptors.
Main Methods:
- Modification of endogenous EF-2 to create toxin-resistant stem cells.
- Engineering stem cells to secrete PE-cytotoxins targeting interleukin-13 receptor subunit alpha-2 or epidermal growth factor receptor.
- Utilizing optical imaging to monitor protein synthesis inhibition and GBM cell viability in vivo.
- Employing biodegradable synthetic extracellular matrix (sECM) for stem cell encapsulation and delivery.
Main Results:
- Efficacy of PE-targeted cytotoxins correlated with cognate receptor expression levels in GBM.
- Stem cell-encapsulated IL13-PE released from sECM significantly increased long-term survival in a GBM resection model compared to protein infusion.
- Multiple patient-derived GBM lines demonstrated responsiveness to the engineered stem cell treatment.
Conclusions:
- Integrating stem cell engineering, multimodal imaging, and PE-cytotoxin delivery offers a novel strategy for GBM therapy.
- Engineered stem cells secreting targeted PE-cytotoxins represent a potential advancement in glioblastoma treatment.
- This approach addresses limitations of previous therapies, showing promise for clinical translation.
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