Abstract
The increasing need for long lasting injectable #softtissue fillers
for the treatment of wrinkles and skin defects, gastric reflux, urinary
and
fecal incontinence, and other indications requires a critical discussion
of #biocompatibility based on science. Since biological fillers made of
collagen will be absorbed over time, medium- and long-lasting
#biomaterials have been developed in recent years. Particles of irregular
shape
and rough surface structure tend to initiate severe and early foreign
body reactions with scattered giant cells (“#frustratedmacrophages”). On
the other hand, biologically inert #microspheres with smooth surfaces are
encapsulated by macrophages and fibrous tissue and will be kept in
place. A review of the literature shows that most injected microspheres
and particles of different chemical nature and a diameter of 20 to 65μm
are #phagocytosed by macrophages. Particles smaller than 20μm are also
phagocytosed but are transported by macrophages to regional lymph
nodes, liver and/or lungs. Since 1 gram of medium size microspheres of
40μm has a surface area twice as large as 1 gram of microspheres of
125μm in diameter, the stimulus for associated tissue in growth is
doubled. Therefore, approximately 75% of the filler volume of a medium
size
microsphere implant consists of the body’s own connective tissue,
whereas only 40% of the filler volume #encapsulatinglargerbeads is made
up of fibrous tissue.
#Biocompatibility of Injectable #Microspheres by Gottfried Lemperle in BJSTR
