CBIO-46SPINDLE CELLS IN EARLY C6-GBM GROWTH ARE STEM CELLS - FUNCTIONAL STUDY WITH MITOCHONDRIAL VOLUME FOR THERAPEUTIC PURPOSE

Abstract

OBJECTIVE: Recurrence of glioblastoma multiforme (GBM) after total resection is postulated to originate from precursor cells existing in surrounding brain tissue. The authors have found spindle cells in the early stage of rat C6 GBM growth, resembling spongioblasts, the origin of GBM (Bailey and Cushing, 1926). They are stem-like cells with positive CD15 staining, and should be the primary target for treatment in experimental animals (Poster at SPNO meeting in May). Currently, spindle cells are functionally evaluated by mitochondrial volume studies for future development of therapeutic tactics. METHODS: 1. C6 cells were cultured in MEM solution, and morphological cell changes were studied with and without temozolomide (TMZ) treatment. 2. Mitochondrial volume of C6 cell in these conditions was measured by mitochondrial mass specific fluorescence probe. 3. C6 cells were implanted into rat's brain and observed the growth in the normal brain tissue. RESULTS: 1. Spindle cells grew in early period, and formed syncytiums. As syncytiums multiplied, mitotic cells began to appear, and typical GBM features developed. During TMZ treatment, multiform cells were mostly destroyed, while spindle cells survived. 2. By TMZ treatment, the number of survived C6 cells decreased, but the volume of mitochondria per unit of C6 cells increased, as the concentration of TMZ increased. 3. The same cell growth pattern was identified in implanted tumor, as seen in cultured cells growth. DISCUSSION AND CONCLUSION: 1. Histologically CD15-positive spindle cells have much higher resistance for survival against TMZ than fully developed multiform cells. 2. Increased mitochondrial volume in survived C6 cells is likely related to metabolic activation of spindle cells under TMZ treatment. 3. The control of mitochondrial hyperactivity of C6 cells should be one of the important means for GBM treatment in experimental GBM, and probably in humans.