Minimally Invasive Silk Biomaterials for Soft Tissue Augmentation
filler materials have long been used to treat soft tissue defects such as facial
scaring, skin fatigue and volume loss. The overwhelming interest in these materials has
led to an increase in novel bio-inspired platforms to improve filler material
integration and efficacy in modified tissue. This project focused on designing a dynamic
array of injectable silk-based materials ... read morefor soft tissue augmentation and
reconstruction. Silk fibroin is a naturally derived, fibrous protein which is
non-immunogenic and FDA-approved for reconstructive surgery. Furthermore, the processing
capabilities of silk allow for the formation of a versatile set of material formats,
such as films, tubes, hydrogels and sponges. Three material formats were optimized for
minimally invasive tissue bulking. Elastomeric silk hydrogels were formulated for
cervical tissue bulking towards preterm birth prevention in patients with cervical
insufficiency. Hydrogels were able to increase tissue volume of cervical samples without
causing excessive stiffening, ultimately restoring the native properties of the cervix.
Shape memory silk sponges were designed to express high flexibility and volumetric
swelling in aqueous media. Under high compressive stress (up to 90% uniaxial strain),
silk sponges could recovery up to and beyond their original volume without plastic
deformation. Additionally, sponges promoted cellular infiltration and tissue deposition
in vivo, allowing regeneration of the tissue surrounding the wounded area. Gradient
porosity silk catheters were fabricated for integration with adipose tissue during fat
grafting procedures. Catheters could sustain release of a cargo therapeutic for up to
two weeks, and the gradient porosity allowed spatial control over the location of drug
release along the tube length. Silk catheters improved in vivo volume retention of
transplanted adipose tissue by supporting viability with targeted dexamethasone
delivery. Finally, the mechanism behind creating flexible protein-based materials using
naturally derived plasticizers was investigated. The findings reported here support
future development of more advanced biomimetic tissue fillers capable of accommodating
minimally invasive insertion strategies.
Thesis (Ph.D.)--Tufts University, 2016.
Submitted to the Dept. of Biomedical Engineering.
Advisor: David Kaplan.
Committee: Fiorenzo Omenetto, Kacey Marra, Michael House, and Darryl Williams.
Keyword: Biomedical engineering.read less