This study aimed to evaluate the safety and therapeutic potential of autologous human adipose-derived mesenchymal stem cells (haMSCs) in patients with osteoarthritis. Safety and efficacy of haMSCs were preclinically assessed in vitro and in BALB/c-nu nude mice. 18 patients were enrolled and divided into three dose groups: the low-dose, mid-dose and high-dose group (1 × 10⁷, 2 × 10⁷ and 5 × 10⁷ cells, respectively), provided three injections and followed up for 96 weeks. The preclinical study established the safety and efficacy of haMSCs. Intra-articular injections of haMSCs were safe and improved pain, function and cartilage volume of the knee joint, rendering them a promising novel treatment for knee osteoarthritis. The dosage of 5 × 10⁷ haMSCs exhibited the highest improvement (ClinicalTrials.gov Identifier: NCT01809769).