Biomedical Engineering Reference
In-Depth Information
Time
(week)
section
number
Scaffold
disaggregation
tissue
necrosis
tissue
ingrowth
fibrationinflammatory cell type
2
2
yes
lymphocyte and macrophageno
no
yes
4
2
yes
lymphocyte and macrophageyes
no
yes
6
2
yes
lymphocyte and macrophageyes
no
yes
8
2
yes
mosly macrophage
yes
no
yes
Table 2. histopathology observation
Porous scaffols made by silk fibroin can be formed into different pore size and porosity,
which could meet the needs of different histocytes during repairing process. Porous
structure is also helpful to the exchange of nutrient substance among different parts of
scaffolds. So we choose the porous silk fibroin scaffold as the research object.
Biological material will be treated as foreign matter when implanted in the body, even if its
biocompatibility is perfectly good. Therefore, foreign body reaction will be inevitable
surrounding the material. The strength and extent of foreign body reaction are closely
related to its biocompatibility and biodegradablity. So, we evaluate the tissue reaction and
material change after implantation by fibrous encapsulation, granulation formation
，
tissue
fibrosis, type of inflammantary cells, tissue necrosis and tissue ingrowth, morphological
changes and disaggregation of the scaffolds.
We found that wet porous fibroin scaffold was soft in texture, and could be easily cut into
different forms to fit the need of implantation while the operation was performed. Tissue
reaction around the materials was slight when we removed the scaffold, and the surface of the
material was wrapped up by semitransparent fibrous membranes. The porous fibroin
scaffolds were eosinophilic stained by HE. Its surface was irregular. And there are lacunes of
different size inside the material. Chronic inflammation reaction occurred, mainly
lymphocytes and macrophages could be found around the material. And fibrous capsule
could be observed. After two weeks of implantation, blood capillary could be found proliferate
into the lacuna of the material, and the fibroblasts also attached to the irregular surface of the
material. These phenomena became more and more obvious as time went by, which showed
that the surface texture of porous fibroin was favourable for interstitial cell to grow on.
Moreover, the porous structure of the scaffold made the material permeable, which could
probably cause the exchange of the nutrition and metabolite through the scaffold that lead to
active tissue ingrowth. This may also be a plus factor for tissue regeneration.
Because the fibroin scaffolds were formed by protein and could hardly be separated from
surrounding tissues, histopathology observation was performed after experiment instead of
quantitative determination. During eight-weeks' observation, the scaffold disintegration
started from the fourth week. But there was still no obvious change inside the scaffold
structure until the eighth week, which indicated to us that we should set the observation
period much longer to get more information about the degradation of fibroin porous
scaffold in further research. We didn't make effective statistical analysis about the quantity
and type of inflammatory cells surrounding the scaffold for the number of samples was too
small. Moreover, according to the requirements of different tissue repair, the pore size and
porosity of porous scaffolds should be different. And materials with different structure may
cause different result in tissue reaction, tissue regeneration and material degradation. These
are also challenging questions that need to be considered in further experiment.
