Abstract 117: Therapeutic Impact of Direct Cell Sheet Transplantation Derived from Bone Marrow Stromal Cells for Cerebral Infarct in Rats

Abstract

Background and Purpose - Less-invasive and efficient donor cell delivery is quite important for the clinical application of cell transplantation therapy. Recently, cell sheet technology has gained a great interest as a novel tissue engineering technology, but there are no studies that evaluate the validity of the bone marrow stromal cell (BMSC) sheets as the donor for cerebral infarct. The aim of this study is to assess whether the BMSC sheet can be an alternative transplantation technique to promote functional recovery after cerebral infarct. Methods - The BMSC were harvested from green fluorescence protein (GFP)-transgenic rat and were cultured on a temperature-responsive culture dishes. The mono-layered BMSC sheet was detached by changing the temperature of culture dishes, and was histologically analyzed. Next, the SD rats were subjected to permanent middle cerebral artery occlusion and were divided into 3 experimental groups. Thus, the vehicle or BMSC suspension was stereotactically transplanted into the ipsilateral striatum, or the BMSC sheet was directly transplanted onto the ipsilateral intact neocortex at 7 days after the insult (n=9, 9, 7, respectively). Motor function was assessed for 28 days after transplantation. Finally, histological analysis was performed. Results - BMSC sheet was composed of 9.8 ± 2.4 x10 5 cells (n=10). Stereotactic injection of BMSC significantly enhanced the recovery of motor function after cerebral infarct. Likewise, non-invasive cell sheet transplantation also significantly promoted functional recovery. The therapeutic effect was comparable to stereotactic cell transplantation. Fluorescence immunohistochemistry revealed that the GFP-positive cells were densely distributed in the dorsal neocortex adjacent to cerebral infarct in both groups. Double fluorescence immunohistochemistry demonstrated that the majority of engrafted GFP-positive cells were positive for NeuN and morphologically simulated the neurons in both groups. The density of reactive astrocytes in the ipsilateral striatum was less pronounced in cell sheet transplantation group than in stereotactic transplantation group. Conclusion - These findings strongly suggest that cell sheet technology would make it possible to non-invasively deliver the BMSC into the infarct brain and to yield significant therapeutic effects, when compared with stereotactic injection of cell suspension. The technology may be a clinically valuable and less-invasive construct for non-invasive and efficient cell delivery to regenerate the infarct brain.