Pengaruh Bone Marrow Mesenchymal Stem Cells Terhadap Tunika Intima dan Muskularis Arteri Intrakranial : Uji Eksperimental pada Tikus Wistar Jantan Mormotensi = The Impact of Bone Marrow Mesenchymal Stem Cells to Intracranial Arteries : An Experimental Study of Tunica Intima and Tunica Muscularis in Normotensive Rats