Stem Cell Therapy: A Primer for Interventionalists and Imagers

MRI Guided Focused Ultrasound-Mediated Delivery of Therapeutic Cells to the Brain: A Review of the State-of-the-Art Methodology and Future Applications

Stem cell and immune cell therapies are being investigated as a potential therapeutic modality for CNS disorders, performing functions such as targeted drug or growth factor delivery, tumor cell destruction, or inflammatory regulation. Despite promising preclinical studies, delivery routes for maximizing cell engraftment, such as stereotactic or intrathecal injection, are invasive and carry risks of hemorrhage and infection. Recent developments in MRI-guided focused ultrasound (MRgFUS) technology have significant implications for treating focal CNS pathologies including neurodegenerative, vascular and malignant processes. MRgFUS is currently employed in the clinic for treating essential tremor and Parkinson's Disease by producing precise, incisionless, transcranial lesions. This non-invasive technology can also be modified for non-destructive applications to safely and transiently open the blood-brain barrier (BBB) to deliver a range of therapeutics, including cells. This review is meant to familiarize the neuro-interventionalist with this topic and discusses the use of MRgFUS for facilitating cellular delivery to the brain. A detailed and comprehensive description is provided on routes of cell administration, imaging strategies for targeting and tracking cellular delivery and engraftment, biophysical mechanisms of BBB enhanced permeability, supportive proof-of-concept studies, and potential for clinical translation.

Current Indications, Techniques, and Imaging Findings of Stem Cell Treatment and Bone Marrow Transplant

The role of stem cell therapy in the treatment of hematologic and nonhematologic conditions is ever increasing. A thorough knowledge of the applications of stem cells and transplant physiology is essential for understanding the imaging manifestations. Stem cell imaging includes molecular imaging, and diagnostic and interventional radiology. It is possible to make a diagnosis of various complications and diseases associated with stem cell transplant. This article presents a simplified overview of stem cell applications and techniques with focus on hematopoietic stem cell transplant imaging.

Interventional stem cell therapy

The ability to deliver cells in appropriate doses to their targeted site of action is a well-known obstacle to optimising stem cell therapy. Systemic administration of cells results in pulmonary "trapping," which significantly decreases the number of available circulating cells to impact underlying disorders. Directed delivery of stem cells in interventional radiology may provide an additional option for bypassing the lungs, as well as introduce novel potential avenues for decreasing doses required to effect cellular therapy, efficiently obtain local paracrine effects, and/or to simplify targeting strategies.

Pancreatic islet cell transplantation: an update for interventional radiologists

Pancreatic islet cell transplantation is a promising cellular-based therapy for type 1 diabetes mellitus. This procedure involves portal venous injection of islet cells and affords 1-year insulin independence in as many as 80% of recipients. Although transplant surgeons represent historical drivers of islet therapy, requirement for image guidance and transcatheter techniques has fostered collaboration with interventional radiologists, who are positioned to play a significant role in clinical performance of islet transplantation and in basic science research in this field. This review article aims to familiarize interventional radiologists with islet cell transplantation patient selection, procedure technique, clinical outcomes, and future clinical and research avenues.

Combination of cell delivery and thermoinducible transcription for in vivo spatiotemporal control of gene expression: a feasibility study

PURPOSE

To demonstrate the feasibility of combining in situ delivery of genetically modified cells into the rat kidney, to induce expression of a reporter gene under transcriptional control of a heat-inducible promoter activated with magnetic resonance (MR)-guided focused ultrasonography (US), and to demonstrate in vivo the local expression of the synthesized protein.

MATERIALS AND METHODS

Experiments were conducted in agreement with the European Commission guidelines and directives of the French Research Ministry. C6 cells were genetically modified by incorporating the firefly luciferase (LucF) gene under transcriptional control of a heat-sensitive promoter (human heat shock protein 70B). Engineered cells were injected in the renal artery of a superficialized left kidney (15 rats). Two days later, intrarenal LucF expression was induced noninvasively by local hyperthermia in 15 renal locations in nine rats with focused US and was controlled with MR temperature imaging. Six hours after heating, LucF activity was detected in vivo with bioluminescence imaging.

RESULTS

The genetically engineered C6 cell line was characterized in vitro for LucF expression related to the heating parameters. Changes in renal morphology and hemodynamic parameters as a result of rat kidney superficialization were not significant. Intrarenal temperature measurement at the focal point followed the scheduled temperature in 13 of 15 cases. On bioluminescence images, LucF activity was present only in heated regions. The level of LucF expression was also dependent on heating parameters. Substantial tissue damage was noted at histologic analysis in only the two cases in which temperature control was inadequate.

CONCLUSION

A strategy combining cell delivery of a transgene and a thermosensitive promoter that can be locally activated with MR-guided focused US is able to induce in vivo gene expression controlled in space and time.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100767/-/DC1.