Osteoarthritis (OA) is a severe, chronic, and progressive disease that eventually leads to disability. OA is characterized by joint pain, stiffness, limited mobility with effusion, and inflammation. It has a negative physical and psychological impact which results in a reduced quality of life. OA occurs as an imbalance between the formation and degeneration of chondrocytes and extracellular matrix which leads to progressive destruction of articular cartilage. OA symptoms were routinely managed using pharmacologic treatments including hyaluronic acid (HA) and platelet rich plasma (PRP) injections. Recent guidelines have recommended against the use of these agents. Both treatments are mainly given for pain relief and have minimal effects on stopping the progression of OA; hyaluronic acid (HA) leads to a small reduction in knee osteoarthritis pain compared with placebo, while PRP, did not result in a significant difference in symptoms or joint structure. These findings do not support broad use of them for the treatment of knee osteoarthritis.

Mesenchymal Stromal Cells (MSCs) are one of the emerging, regenerative therapies that aim to treat, prevent and even reverse OA through their immunomodulatory properties that reduce inflammation and promote angiogenesis. MSCs are proven to regulate the body's immune response in many diseases and exert anti-inflammatory effects. These immunomodulatory properties are mediated via paracrine mechanisms. Following their discovery over 50 years ago, mesenchymal stromal cells (MSCs) have become one of the most studied cellular therapeutic products by both academia and industry due to their regenerative potential and immunomodulatory properties. The promise of MSCs as a therapeutic modality has been demonstrated in a number of preclinical data as well as in clinical setting. Stromaforte cells which will be used in this study is developed within CELLCOLABS AB and were generated following the same protocol established over the last 20 years by scientists CELLCOLABS AB at the Karolinska Institute in Sweden. MSCs showed a very promising effect in patients including vocal folds, GVHD, ARDS, multiple sclerosis and recently in patients severely infected with COVID virus.

The currently completed preclinical studies on animal models showed that intra-articular injection of MSCs can promote cartilage regeneration and reduce joint inflammation to improve the OA function of joints, and no malignant transformation of MSCs has been found as well as randomized double blinded phase I/II clinical studies reported that, the clinical manifestations, radiological and histological scores of OA patients were improved, no graft-related death, tumorigenesis and infection occurred, and no serious adverse reactions were observed. These studies demonstrated safety and tolerability of the MSCs. Based on the above results preclinical and clinical studies, it is planned to conduct this study which has been designed to evaluate the safety and tolerability of intra-articular human allogeneic bone marrow-derived mesenchymal stromal cell product StromaForte in mild-to-moderate stage knee osteoarthritis patients before further clinical development.