Immobilized bioengineered spider silk ion a nanofibrous mesh reduces bacteria adhesion while improving abdominal muscle tissue repair

The loss of the abdominal wall biomechanical properties together with the occurrence of surgical site infections (SSI) after abdominal surgery represents a health problem that must be addressed. Current materials solutions (i.e. implantation of surgical meshes) restore the abdominal wall but also induce significant clinical complications that need to be tackled. Proteins derived from bioengineered spider silk have tremendous potential as drug-free biomaterials [1]. Moreover, the fusion with human-derived antimicrobial peptides (AMP) is an innovative method that confers antimicrobial activity on the materials [1]. In this study, we investigate the antimicrobial potential of immobilized bioengineered spider silk proteins with AMP on nanofibrous meshes (NFM) aiming to simultaneously prevent infections and restore abdominal wall biomechanics simultaneously.

To achieve this goal, a facile functionalization method comprising the immobilization of bioengineered spider silk protein with AMP (6mer-HNP1), as well as bioengineered spider silk protein alone (6mer), on electrospun polycaprolactone (PCL) NFM was employed[2]. Both sides of PCL NFM were activated by exposing them to ultraviolet ozone for two minutes each. The capacity for protein immobilization on the activated NFM was evaluated, and the functionalized mesh was further characterized in terms of antibacterial activity and cytocompatibility[2].

The maximum immobilization capacity of the bioengineered proteins 6mer and 6mer-HNP1 were 200 μg mL−1 and 250 μg mL−1, respectively. The formation of beta-sheets by the spider silk domain was unaffected by protein immobilization on the NFM. Functionalized meshes with 6mer-HNP1 significantly inhibited the adherence and biofilm formation of Methicillin-Resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), demonstrating their antimicrobial potential. In vitro cell studies using a human umbilical vein cell line (EA.hy926) validated the cytocompatibility of the functionalized meshes and the proliferation of muscle-related cells (C2C12 mouse myoblasts cell line) further demonstrating their biological potential. Overall, the use of functionalized meshes with bioengineered spider silk proteins can be a safe and effective alternative to the development of high-performance surgical meshes for challenging abdominal wall repair surgeries.

Acknowledgements:

 The authors would like to thank the contributions to this research from the project “TERM RES Hub – Scientific Infrastructure for Tissue Engineering and Regenerative Medicine”, reference PINFRA/22190/2016 (Norte-01-0145-FEDER-022190), funded by the Portuguese National Science Foundation (FCT) through OE component in cooperation with the Northern Portugal Regional Coordination and Development Commission (CCDR-N), for providing relevant lab facilities, state-of-the-art equipment and highly qualified human resources, and through OE component under the project NORTE-01-0145-FEDER-000055, PTDC/BTM-MAT/2844/2021; ARF grant SFRH/BPD/100760/2014.

References:

[1] Franco, A.R. et al.,  Acta Biomater. 99, 236-246 (2019).

[2] Casanova, M.R. et al., Npj Regen. Med. 2021, 6 (2021).