The biomechanical performance of the skin depends essentially
on the integrity of the dermal extracellular matrix. This matrix is
arranged in a dense network of interlinked collagen (types I and III)
and elastin fibres containing water-retaining proteoglycan and
glycanmacro-aggregates.Withage,the collagennetworkundergoes
re-organisation (density, orientation), resulting in a reduction in
collagen and proteoglycan content [1], accompanied by an increase
in denatured and degraded collagen [2]. These changes lead to a loss
of matrix volume and, consequently, to a deterioration in mechanical
properties [3], which may induce changes in cell metabolism.
Indeed, a link between the mechanical stress exerted on different
types of tissues and neocollagen production has been suggested.
Well-known examples are provided by studies on the adaptive
response of articular tissue which show that certain types of strain
clearly stimulate the anabolic response [4]. Likewise, experimental
data have confirmed the anabolic effect of mechanical strains on the
extracellular matrix of fibroblasts cultured in a 3-dimensional
network (collagen lattices) [5]. Furthermore, owing to the high
degree ofbiocompatibilityofhyaluronic acid,the anabolic responses
of tissues after injection appear very different from those seen with
other types of implants, which usually lead to the formation of a
fibrotic shell [6].