Assessment of platelet growth factors in supernatants from rehydrated freeze-dried equine platelets and their effects on fibroblasts in vitro.
OBJECTIVE
To determine whether platelet growth factors are preserved in supernatants obtained from rehydrated trehalose-stabilized, freeze-dried (lyophilized) equine platelets and whether those growth factors stimulate fibroblast proliferation and migration and enhance fibroblast-associated contraction in a collagen gel assay.


METHODS
6 clinically normal adult horses.


METHODS
Blood samples were obtained from 6 horses, and washed platelets were prepared via differential centrifugation. Washed platelets were freeze-dried in a physiologic buffer with a mixture of trehalose and polyethylene glycol 4000. Rehydrated platelet supernatants and releasates prepared from fresh washed platelets stimulated with thrombin or platelet-activating factor were evaluated for transforming growth factor beta1 and platelet-derived growth factor-BB by use of ELISAs. Effects of rehydrated freeze-dried platelet supernatants on fibroblast proliferation, migration, and collagen gel contraction were compared with effects of 1%, 2.5%, or 10% fetal bovine serum (FBS).


RESULTS
Supernatants from freeze-dried platelets contained similar amounts of growth factors as thrombin- and platelet-activating factor-stimulated platelet releasates. The supernatants significantly enhanced fibroblast proliferation and migration in a scratch assay, compared with FBS-free control or low (1%) FBS conditions. Additionally, supernatants from freeze-dried platelets enhanced contraction of fibroblast-seeded collagen gels, compared with the effect of 1% FBS.


CONCLUSIONS
The preparation technique preserved platelet growth factors, enhanced fibroblast proliferation and migration, and improved fibroblastseeded collagen gel contraction under conditions of low FBS concentration; these platelet supernatant preparations may prove useful as an aid to conventional wound management.
Tablin
Fern
F
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Walker
Naomi J
NJ
Hogle
Sara E
SE
Pratt
Suzanne M
SM
Norris
Jeffrey W
JW
D000818:Animals; D001792:Blood Platelets / Q000737:chemistry*; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002498:Centrifugation / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000187:drug effects; D005612:Freeze Drying / Q000662:veterinary; D006736:Horses; D010982:Platelet-Derived Growth Factor / Q000032:analysis* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000032:analysis* / Q000494:pharmacology
D010982:Platelet-Derived Growth Factor; D053773:Transforming Growth Factor beta1