15928
To study the tissue regeneration efficacy of the engineered PLLA fiber matrix , human dermal fibroblasts are used to simulate partial skin graft .
 Chemical: PLLA
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: PLLA 
Answer:
 Chemical: PLLA