Biomedical Engineering Reference
In-Depth Information
Fig. 8.10
Contraction kinetics in the presence (
grafted
) and absence (
ungrafted
) of a collagen
scaffold that was very similar in structure to DRT. Wound contraction was dramatically delayed
when full-thickness skin wounds were grafted with the highly porous collagen scaffold. Scar for-
mation was not observed; instead, a small mass of dermis was formed. This is believed to be the
first observation of induced stroma regeneration in the adult mammal. (Yannas 1981)
collagen scaffold with highly specific structure was in contact with the wound; no
such powerful blockade of contraction was observed when other collagen scaffolds,
even slightly differing in structure, were employed. Likewise, scar formation was
also blocked when appropriately structured collagen scaffolds were used in these
wounds.
8.4.1
Skin Wounds: Healing in the Presence of DRT
An early observation of a dramatic delay in contraction of a full-thickness skin
wound was reported when the guinea pig skin wound was grafted with an early
version of DRT, a collagen scaffold with highly porous structure (Fig.
8.10
, Yannas
1981; Yannas et al. 1977, 1979, 1981, 1982). Although the delay in contraction was
very sizeable, the wound eventually closed by contraction and histological exami-
nation showed formation of a small mass of neodermis with absence of scar.
Somewhat later, a version of DRT seeded with autologous keratinocytes (“KC-
seeded DRT”) was seeded at density levels of 5 ⋅ 10
4
up to 1 ⋅ 10
6
seeded cells per
cm
2
graft area and studied in the guinea pig model (Orgill 1983; Yannas et al. 1982,
1989). The result of seeding DRT with KC on the healing outcome was quite un-
expected. In Fig.
8.11
, the KC-seeded active scaffold (DRT) entirely controlled
contraction of the square wound, retaining the square shape almost completely,
though not perfectly, and resulted in new tissue synthesis that closed the wound. By
