<qa>  What is the name of the study that is to isolate and expand MSCs from infThis study is to isolate and expand MSCsRegStem from infrapatellar fat pad of subject. When the number of MSCs expands to 1×108, cell will be cryopreserved in the liquid nitrogen tank until all release tests passed. On the distribution day, cell will be thawed and injected into joint cavity of patient 5×107. Subjects will be monitored after MSC product infusion of seven days, one month, six months and one year. The monitoring items include the changes of knee by appearance, X-ray and MRI of knee and pain improvement by questionnaire. 