Tissue Response to Implanted Collagen Matrix in Implant Based Breast Reconstruction * A Histological Study

Implant based breast reconstruction after skin sparing mastectomy is frequently
performed in breast cancer patients. Recently, the use of a collagen matrix
inlay has been introduced with the aim to improve tissue coverage of the
implant, and to enable the surgeon to shape the breast in a more natural way.
In Europe, a collagen sheet manufactured from porcine skin (Strattice*) is most
commonly used for this purpose. Clinical results as described in literature so
far have been mostly positive. It is assumed that the collagen matrix is
rapidly invaded by host cells, and angiogenesis occurs within a time frame of
less than 6 months. Since the collagen sheet is placed between skin on the one
side and the implant on the other side, ingrowth can occur from the skin side
only. To date, there has not been a detailed histological analysis of the
tissue response to the collagen matrix inlay in humans who received
implant-based breast reconstruction. It is important to understand the dynamics
of tissue ingrowth and the behavior in situ of the implanted biomaterial. In
addition, the occurrence and severity of a foreign body response should be
investigated. Recent literature suggests lower capsular contracture rates with
the use of Strattice. Yet, the mechanism behind this finding remains unclear.
Both foreign body response and bacterial contamination are considered to play a
role.

The aim of this study is to investigate the host tissue response to the
implanted collagen inlay in implant based breast reconstruction. Secondary, we
want to investigate if the presence of capsular formation is associated with
the presence of bacterial contamination.
More specifically we want to do histological assessment of:
- Revascularisation of the Strattice* sheet.
- Immune cell response
- Formation of granulation tissue (fibroblast infiltration)
- Extent of collagen remodelling (fibrosis)
- Bacterial colonization

The study is an observational pilot-study.

The risk of this intervention is negligible. There are no benefits for the
patient. General benefit is that we obtain more knowledge about the human
tissue response to implanted collagen matrices.