Chondrogenesis-inductive nanofibrous substrate comprising autologous TGF-b3 and IGF-I from platelet lysates

Articular cartilage is a connective tissue with low self-regeneration potential due to its avascular nature and lack of progenitor cells ^[1]. Therefore, cartilage regeneration is far to be achieved and then it is an important candidate for tissue engineering and regenerative medicine (TERM) strategies. TGF-b3 and IGF-I have been identified as important proteins on the regulation of cartilage development and on the homeostasis of mature articular cartilage ^{[2, 3]}. Therefore, the synergetic effect of the growth factors (GFs) in a biomaterial substrate is hypothesized to lead to the successful chondrogenic differentiation of mesenchymal stem cells (MSCs). The leading goal of this study is to develop a multi-functionalized electrospun nanofibrous mesh (NFM) with chondrogenic potential, through the binding of autologous TGF-b3 and IGF-I. For that, defined antibodies were immobilized at the surface of NFMs, capable to specifically select only the GFs of interest from a complex biological fluid (i.e. platelet lysate - PL). The maximum immobilization capacity of each antibody was 4 mg/mL for both antibodies. The anti-TGF-b3 and anti-IGF-I antibodies were also immobilized over the same structure in a mixed fashion at 1:10 proportion (0.4mg/mL anti-TGF-b3 : 3.6mg/mL anti-IGF-I). The bioactivity of immobilized antibodies was tested by using recombinant proteins (rGF), achieving a binding efficiency of 36% for TGF-b3 and 44% for IGF-I. Similar results were observed for GFs captured from PL by NFMs functionalized with single or mixed antibodies. The chondrogenic potential of this bi-functionalized biomaterial system (Single or Mixed, with TGF-b3 and IGF-I captured from PL or rGF) was further assessed by culturing human bone marrow-derived MSCs during 28 days without further induction. Bare NFMs cultured with hBMSCs under standard chondrogenic differentiation medium supplemented with TGF-b3 and IGF-I were used as positive control. Biological results indicate that the bio-functional systems are more effective when compared to control condition.

^[1] Correa, D. and S.A. Lietman, Semin Cell Dev Biol, 2016; ^[2] Petrou, M., et al., Regen Med, 2013; ^[3] Longobardi, L., et al., J Bone Miner Res, 2006.