gms | German Medical Science

Objectives: Bioactive glass scaffolds could support cartilage repair by continuous ion release. The novel degradable bioactive glass (patent DE 10 2018 114 946 B3, 2019) CAR12N was designed by the research team to specifically support cartilage formation without hydroxy apatite deposition. Since in vitro results with highly porous CAR12N scaffolds were very promising biocompatibility and in vivo behavior were investigated in this study.

Methods: CAR12N, CAR12N reinforced by Poly(D-L-lactide-co-glycolide)(PLGA) infiltration (CAR12N+PLGA) (patent submitted) or supplemented with CaO/MgO ions (+CaO/MgO) and the commercially available reference BG1393 were dynamically pre-colonized for 7 days with porcine articular chondrocytes (pACs) or undifferentiated human mesenchymal stem cells (hMSCs), before they were subcutaneously implanted (subnuchal) into female athymic nude mice for six weeks. All animal experiments were approved by the local Animal Experimentation Board and were performed in accordance with the legislation on protection of animals (RUF-55.2.2-2532-2-1447-24). Mice weight development was weekly monitored. Explanted scaffolds were examined according to their size, shape, stability and tissue color using a macroscore, weight, cell vitality, histologically, DNA and sulphated glycosaminoglycan (sGAG) contents. Histopathology of explanted organs (liver, lung, spleen, kidney) was performed.

Results and conclusion: The dry weight of the uncolonized CAR12N+PLGA scaffolds was significantly higher than the weight of +CaO/MgO and the BG1393 scaffolds, probably due to the addition of PLGA functionalization. Cell viability on pAC and hMSC pre-colonized scaffolds before implantation was more than 85%. Scaffold areas colonized with viable hMSC were higher for BG1393 scaffolds compared to the other scaffold variants. Mice showed regular weight development, wound closure after scaffold implantation and no histopathological organ alterations after explantation. The explanted BG1393 scaffolds were significantly heavier in comparison to the other 3 groups not only the controls (uncolonized), the pAC but also in the hMSC pre-cultivated ones. The surface of all explanted scaffolds carried vital cells. The macroscore of the uncolonized +CaO/MgO scaffolds was the highest in comparison the other groups, while more sGAGs per cell were measured in the BG1393 scaffolds in each group in comparison to all other scaffold types. Histologically, cartilage like tissue formation could be shown in the scaffold variants seeded with pAC, particularly in +CaO/MgO, with lower ECM density in BG1393. In contrast to BG1393 the CAR12N scaffold variants showed lesser Ca++ deposition by Alizarin red staining. Presence of few foreign body giant cells was seen in CAR12N+PLGA scaffolds.

All tested BG scaffold were biocompatible. Neocartilage formation could be demonstrated with CAR12N variants, in vivo underlining its potential for cartilage regeneration.