Biomedical Engineering Reference
In-Depth Information
3. Biocompatibilty research of silk fibroin
Silk fibroin has been utilized as natural biomaterial in tissue engineering applications. Many
researches have been made in vitro to reveal its attractive properties such as slow-
controllable degradation, mechanical robustness, and inherent biocompatibility
[18-21]
.
For the silk fibroin scaffolds are made up of proteins, those materials which have been
implanted will degrade and could hardly be separated from host tissues, that made the
study of histocompatibility difficult. Therefore, few report can be found about research on
biocompatibility and degradation of porous fibroin scaffolds in vivo
[4,22]
.
4. Our in vivo research on the histocompatibility of silk fibroin
4.1 Materials and methods
Laboratory animals:
8 healty female Sprague-Dawley rat, body weight 220g
～
250g, get from
department of laboratory animal medicine, Fudan University
Preparation method of porous silk fibroin scaffold:
After degummed, the raw silk was
dissolved into aqueous solution of LiBr (lithium bromide). The silk fibroin solution was
adjusted to the concentration of 20% after filtration and concentration. Then n-butyl alcohol
was added into the solution as volume ratio of 2: 1. Mixed solution was added into self-
made mould after low-speed agitation, and white porous scaffold was obtained after freeze
drying. The average pore size of the scaffold was between 10 and 20um.
Material prepration:
We cut the porous silk fibroin scaffolds to 1cm×1cm squares (about 1
mm thick), infused the material into 75% ethanol solution for 0.5 hour, then immersed the
materials into 0.9% NaCl water for 24 hours.
Technique:
After peritoneal injection anesthesia, we longitudinal incised the skin of back
open, blunt dissected surrounding tissues, and buried the porous silk fibroin scaffolds
subcutaeous. Then we sew up the incision and raised the animals in different captivities.
Histological examination
The rats were executed 2,4,6,8 weeks after operation. General
observation and hematoxylin and eosin stain histological examination was performed.
4.2 Result and discussion
General observation
Animals recovered well after operation. Throughout the period of
implantation, all scaffolds were well tolerated by the host animals and immune responses to
the implants were mild. No obvious systemic reaction, abnormal eating and sleeping
behaviors were found. The implant sample in animals' back hunched mildly. The wounds
and surrouding skin healed well when drawing materials at different times (figure 1). No
obvious hyperemia, seepage or purulent exudates signs were found in surrounding skin
and muscular tissue. The surface of the scaffolds was wrapped up by the thin,
semitransparent fibrous membranes. There was no obvious change in shape and appearance
after implanting(figure 2). The inflammatory reaction surrounding the tissue was slight.
And no obvious granulation was found.(table 1)
The second week
: Fibroin scaffold is eosinophilic staining. The surface is not regular while
there are big or small pores inside. Hematoxylin-eosin staining microscopic
examination(table 2). Fibroblast grows adherently on the surface of the material. The
surrounding tissue hyperplasticly changes, inflammatory cell infiltrate is visible, most of
which are lymphocytes and macrophages. No signs of tissue necrosis are found.(figure 3,4)
