This clinical trial is conducted to assess the long-term safety of "jointstem" in patients with degenerative knee arthritis who participated in the previous BS-JS-IIT1 investigator initiated trial.

JOINTSTEM is injectables for an OA treatment that uses autologous adipose-derived mesenchymal stem cells. As it does not use allogenic tissues and is cultured without additional genetic modification, it is classified as 'autologous cell therapy' and is completely free of immunologic rejection.

This clinical trial is planned to follow-up the long-term safety of "jointstem" in patients with degenerative knee arthritis who participated in the previous BS-JS-IIT1 investigator initiated trial.

Subjects who participate in the BS-JS-IIT1 study and agree to this extension test in writing will be assessed for safety by conducting laboratory tests, vital signs, physical examinations and adverse events every 12 months after Visit 1.

However, after unblinding of the BS-JS-IIT1 investigator initiated trial, subjects in the control group (placebo administration) will terminate the follow-up of this extended clinical trial and conduct routine treatment for degenerative knee arthritis at the discretion of the researcher. Appropriate measures and follow-up observations shall be implemented for abnormal reactions occurred during this extended test period until they are terminated (such as the loss of the relevant adverse event or inability to conduct follow-up investigations).

Inclusion Criteria:

• Participants of Jointstem IIT by arthroscopy (BS-JS-IIT1)
• Participants who signed informed consent document of this study

Exclusion Criteria:

• No applicable