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Recombinant spider silk for biomedical applications - from functionalizing surfaces of synthetic materials to in vitro modelling of tissues

Time: Fri 2022-05-20 10.30

Location: FR4 (Oskar Kleins auditorium), Roslagstullsbacken 21, Stockholm

Video link: https://kth-se.zoom.us/j/69561519449

Language: English

Subject area: Biotechnology

Doctoral student: Christos Panagiotis Tasiopoulos , Proteinvetenskap, Silk group

Opponent: Professor Antonella Motta, University of Trento, Trento, Italy

Supervisor: Professor My Hedhammar, Proteinteknologi

QC 20220516

Abstract

Spider silk is a natural protein-based material known for its medicinal use and remarkable mechanical properties. Structures made thereof are both strong and elastic and have been shown to be favorable matrices for tissue engineering. As natural spider silk is difficult to obtain, recombinant technology is instead used to produce partial silk proteins. This thesis investigates the use of one such partial spider silk protein functionalized with a cell adhesion motif from fibronectin, FN-4RepCT, to coat the surface of synthetic polymers, as well as self-assemble into nanofibrillar membranes for modelling of tissues in vitro.

In Paper I, the silk protein was shown to self-assemble into coatings with simultaneous entrapment of cells (co-seeding) to functionalize polymeric surfaces. The results showed that the co-seeding approach facilitated the adherence and sustained the viability of cells on surfaces of materials widely used for the manufacture of cardiovascular grafts.

In Paper II, a protocol was developed to enable the formation of nanofibrillar coatings on the surface of membranes intended for guided bone regeneration. This was done by reducing the surface tension of the membranes, allowing for the self-assembly of silk proteins to take place. The silk coating facilitated the adherence, promoted the growth, and mediated the generation of a cell monolayer of tissue representative cells seeded on either side of the membrane.

In Paper III, the self-assembly of the silk protein at the air-liquid interface was shown to form cm-sized free-standing, tough and elastic, nanofibrillar silk nanomembranes, permeable to macromolecules of various sizes, and able to support the establishment of a confluent layer of keratinocytes seeded on either side. In Paper IV, the nanofibrillar silk membranes were shown able to support cell co-culture to generate a model of the blood vessel wall in vitro.

In Paper V, an alveolar-capillary model was established by seeding lung epithelial and endothelial cells on opposite sides of nanofibrillar silk membranes. The results showed the formation of an in vivo like tissue through the expression of junctional complexes and the production of essential surfactants. The silk membranes were also for the first time integrated into a microfluidic device to expose the endothelium to flow-induced shear stresses.

Altogether, the work conducted in this thesis shows promise to the use of the FN-4RepCT silk protein both for coating surfaces of bio-inert synthetic polymeric materials and forming thin and nanofibrillar membranes for the engineering of tissues in vitro.

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