Studies of Nutrient Media for Tissue Cells in Vitro II. An Improved Protein-flee Chemically for Long-Term Cultivation of Strain Defined Medium L-929 Cells

F u n d a m e n t a l p r o b l e m s of g r o w t h a n d t h e sc reen ing of c h e m o t h e r a p e u t i c a g e n t s b e c o m e m o r e n e a r l y de f inab le in precise c h e m i c a l t e r m s w h e n q u a n t i t a t i v e p rocedu re s (5, 9) for e s t i m a t ing p ro l i f e r a t i on are used in t h e p resence of a c h e m i c a l l y def ined b a c k g r o u n d m e d i u m c o m p l e t e l y devo id of a n y p r o t e i n a n d c a p a b l e of s u p p o r t ing p ro l i f e ra t ion . M e d i a of t h i s t y p e h a v e been rep o r t e d f rom t w o l a b o r a t o r i e s (4, 6, 7). I n t h e cont i n u i n g s tud ies on t h e i m p r o v e m e n t of one of t h e s e m e d i a (4) in t h i s l a b o r a t o r y , a d e m o n s t r a t i o n of t h e effect of a c h e m i c a l a g e n t , c r y s t a l l i n e v i t a m i n B12, in t h e p resence of such a c h e m i c a l l y def ined m e d i u m is g iven in th i s pape r . D a t a are p r e s e n t e d f rom b o t h s h o r t t e r m a n d l o n g t e r m e x p e r i m e n t s on t h e mer i t of c o n t i n u i n g to use c e r t a i n c h e m i c a l c o m p o n e n t g roups in t h e i m p r o v e d c h e m i c a l l y def ined m e d i u m c o n t a i n i n g v i t a m i n B12.1 F i n a l l y , c e r t a i n more c r i t i ca l levels of p r o t e i n s u p p l e m e n t a t i o n of t he i m p r o v e d c h e m i c a l l y def ined m e d i u m are explored.