Table 1.

Studied Receptors and Their Binding Growth Factors

Receptorsa	Description	Growth Factor	Concentration in PRP (pg/ml)b	Function in Fibroblasts
TGF-β R1	Similar binding affinities, high affinity for TGF-β1, low affinity for TGF-β2, equivalent to TGF-β receptor 2			Various subforms; TGF-β1 enhances fibroblast proliferation and differentiation and acts as stimulus for type I collagen and firbonection production; TGF-β2 more important for embryonic development
TGF-β-R2a		TGF-β	9184.0
TGF-β-R3	High affinity for TGF-β1 and TGF-β2
PDGF-R	Dimeric receptor in three different conformations (αα, αβ, ββ)	PDGF	3192.9	Enhances fibroblast proliferation and collagen synthesis
FGFR	Including all splicing variants 48 isoforms	FGF	Traces	Potent stimulus of fibroblast proliferation
VEGF-R1	Binds VEGF-A, thought to modulate VEGF-R2 signaling	VEGF	61.6	Expressed in fibroblasts, but role in fibroblast activity still unclear
VEGF-R2	Binds VEGF-A, VEGF-E, VEGF-C; main mediator of VEGF function
VEGF-R3a	Binds VEGF-C, VEGF-D; lymphangiogenetic

This table provides a brief summary on the function of the studied receptors and their growth factors. The more interested reader is asked to refer to reviews of the biology of cell signaling (e.g., Refs. ¹⁸–²¹,³⁰–³²,³⁶–³⁹).

^aNot studied (see text).

^b100 × 10⁹ platelets/L 18–21.