Elderberry (Sambucus nigra) and hawthorn (Crataegus oxyacantha) extract additives in carboxymethyl chitosan scaffolds for osteochondral tissue engineering applications

Advancements in new treatment methods are becoming increasingly necessary due to a longer life expectancy, particularly in the field of osteochondral tissue engineering. In the present study, osteochondral tissue scaffolds with/without the addition of hawthorn or elderberry extracts were fabricated. Poly(ethylene glycol) diglycidyl ether (PEGDE) cross-linked carboxymethyl chitosan hydrogel scaffold matrix was used as a control group. The addition of the plant extracts resulted in open porous structures with pore sizes around 100-450 mu m and elastic modulus between 0.5 and 0.7 MPa, biomimicking the osteochondral tissue. Scaffolds containing either plant extract showed a high swelling tendency (1500-1750%) and a delayed release of the extracts after a week. Furthermore, the weight loss of the scaffolds after an enzymatic degradation for 56 days was similar to 30%. In addition, in vitro biocompatibility analyses were performed using bone marrow-derived mesenchymal stem cells confirming non-cytotoxicity for all the scaffold types. Biochemical assessment of alkaline phosphatase activity and glycosaminoglycan content yielded results consistent with osteochondral scaffold requirements. Finally, immunohistochemical analyses indicated that the plant extract addition, especially elderberry, increased collagen type I and type II formation. As a result, the addition of both hawthorn and elderberry extracts is a promising approach to osteochondral tissue regeneration.