Oo. Olutoye et al., LOWER CYTOKINE RELEASE BY FETAL PORCINE PLATELETS - A POSSIBLE EXPLANATION FOR REDUCED INFLAMMATION AFTER FETAL WOUNDING, Journal of pediatric surgery, 31(1), 1996, pp. 91-95
Fetal dermal wound healing is unique because of its rapidity, minimal
inflammation, and lack of scarring. Cytokines such as transforming gro
wth factor beta (TGF-P) and platelet-derived growth factor (PDGF) evok
e an inflammatory response and scarring when applied to fetal wounds.
Because adult and fetal platelet counts are comparable, the aim of thi
s study was to test the hypothesis that the minimal inflammatory respo
nse seen in the fetus is attributable to differences in the serum cont
ent of cytokines released by fetal platelets. Using Yorkshire swine, b
lood was collected from 10 adults and 10 fetuses at day 60 of gestatio
n (fullterm, 114 days). Platelets were isolated from anticoagulated bl
ood and examined by transmission electron microscopy. Serum was analyz
ed for PDGF-AB and TGF-beta 2 by enzyme-linked immunosorbent assay (EL
ISA), and TGF-beta 1 by I-125 radioimmunoassay. TGF-beta samples were
assayed with and without prior acid activation to determine the total
TGF-beta and the biologically active form of the cytokine. Electron mi
croscopy of adult and fetal platelets showed no gross structural diffe
rences. Alpha granules, which contain cytokines as well as procoagulan
t factors, were present in similar quantities and with the same degree
of homogeneity. The cytokines analyzed were present in all the adult
and fetal sera tested. However, PDGF-AB was present in significantly l
ower concentrations in the fetus (383 +/- 72 pg/mL v 972 +/- 185 pg/mL
in the adult; P <.05). In addition, the fetal samples contained lower
amounts of TGF-beta 1 (13,895 +/- 1,770 v 29,864 +/- 5,050 pg/mL; P <
.05) and TGF-beta 2 (6,758 +/- 734 v 13,407 +/- 1,395 pg/mL; P < .05)
. The majority of TGF-beta was in latent form; the adult sera containe
d significantly more active TGF-beta 1 and active TGF-beta 2 than the
fetal sera. The ratios of active TGF-beta 1 to active TGF-beta 2 were
similar for the adult (22.3) and fetus (18.5). However the ratio of to
tal TGF-beta 1 to total TGF-beta 2 was significantly lower for the fet
us (2.26 v 7.69). The authors conclude that although no gross differen
ces in platelet ultrastructure were noted, fetal porcine platelets rel
ease lower quantities of cytokines into serum. This lower serum cytoki
ne content and the relative concentrations of TGF-beta 1 and TGF-beta
2 may explain, in part, the minimal inflammation and sparse fibrosis c
haracteristic of fetal wounds. These observations provide further insi
ght into the unique fetal response to wounding and may offer alternati
ve avenues to modulate the postnatal wound healing response. Copyright
(C) 1996 by W.B. Saunders Company