The cell culture medium and hydrogel matrix include {HEAD ~ an effective amount} of {TAIL ~ polar amino acids}, the polar amino acids selected from the group consisting of arginine, lysine, histidine, glutamic acid, and aspartic acid 
of
The cell culture medium and hydrogel matrix include { HEAD ~ an effective amount } of { TAIL ~ polar amino acids } , the polar amino acids selected from the group consisting of arginine , lysine , histidine , glutamic acid , and aspartic acid
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH