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two categories: (1) nonpermanent fillers, also named granulomas and palisading granulomas to bovine collagen
replacement fillers (collagen, hyaluronic acid and biological have been reported. Rare systemic complications include
fillers), which has a short duration with typical lengths of flulike symptoms, paresthesias or difficulty breathing,
several months to one year and are eventually reabsorbed and severe anaphylactic shock have been reported after
through macrophage activation; (2) semipermanent injections of bovine collagen. [15,16]
fillers, or stimulatory fillers (polylactic acid and calcium
hydroxylapatite), which have a longer duration of aesthetic The requirement for skin testing before injection to identify
improvements lasting up to years with minimal side effects. patients at risk for allergic reactions and its short duration
They will typically result in a foreign body reaction that elicits of effect, particularly in more mobile areas of the face have
fibroblast activation and collagenesis at the site of injection. restricted the popularity of Bovine collagen’s usage as a skin
[17]
Permanent implants (polymethylmethacrylate, silicone filler. Although human-based collagen was subsequently
and hydroxyethylmethacrylate) could provide long-lasting developed to lessen the chance of hypersensitivity reaction,
revolumization results and could also induce fibrogenesis the demand for collagen rapidly declined in the face of
and collagen production, but with higher potential risk of emerging products that offered long-lasting effects with few
complications. The skilled hands of the experienced plastic side effects.
surgeons/dermatologists are required for injection. [3-5]
Human-derived bioengineered collagen
BIODEGRADABLE FILLERS implants
Human-based collagen implants have been developed in
Biodegradable fillers are impermanent agents than can last recent years, to avoid allergic reactions to bovine collagen.
for a limited time of volume augmentation, from months up Autologen (Collagenesis, Beverly, MA) is an injectable
to 12 months, but will eventually metabolized by the body. autologous human tissue matrix primarily composed of intact
Some of the volume effect is due to a transient inflammatory collagen fibrils that are processed from the patient’s own skin
response to skin fillers with associated edema. However, and harvested during elective surgery. [18,19] Human collagen
these volume effects will diminish soon after injection. [6,7] implants are also obtained from human donor tissues that
Subsequent fibroblast activation and neocollagenesis undergo extensive screening for infectious disease and the
can be another two factors for volume augmentation, material is irradiated before use. The cosmetic effect lasts
but they only result in partial filler engraftment into the about 4 to 7 months, depending on the area of treatment,
surrounding tissue. [8-10] Current biodegradable fillers injection technique, and amount of injected collagen. No
[17]
stimulate neocollagenesis for more sustained aesthetic skin test for hypersensitive reactions is required for human-
improvements and carry a low risk of adverse events or derived collagen products. Local adverse reactions include
serious complications. Although permanent agents offer bruising, erythema, and swelling at the site of injection.
significant clinical benefits, short-term of volume effect, ease Granulomatous reaction at the site of the injection has also
of correction and often reversible in the event of adverse been reported in few cases. [20]
effects make biodegradable fillers attractive to patients and
plastic surgeons worldwide. HA
Crosslinked animal or non-animal derived HA fillers have
Generally, biodegradable filler spread on the market been introduced to the market for more than 20 years in
currently includes: hyaluronic acid (HA), bovoine collagen, the USA and even longer in different countries around the
calcium hydroxylapatite (CaHA) and injectable poly-L-lactic world. Today, HA-based dermal fillers are the fastest non-
acid (PLLA). invasive esthetic procedure in the USA, which still remains
[21]
the most popular dermal filler despite the new injectable
[22]
Bovine collagen fillers with different innovative compounds continues to
Bovine collagen is a resorbable filler. Bovine collagen expand.
was the first facial filler approved by the Food and Drug
Administration (FDA) for the correction of contour HA was first discovered by Karl Meyer, who is considered
irregularities in the USA, [11,12] which has been used as an the father of glycosaminoglycan chemistry, and his assistant
injectable filler for almost 30 years. Originally, Bovine John Palmer. HA is a glycosaminoglycan disaccharide,
[23]
collagen was injected into the dermis and subcutaneous which exists naturally in the body. Approximately 50% of
tissue to correct viral pockmarks, depressed acne scars, total HA is found in the skin, and it is produced by dermal
lipoatrophy, deep nasolabial folds, rhytides, and soft tissue fibroblasts, endothelial cells, synovial cells, adventitial cells,
augmentation. The duration of the augmentation effect is smooth muscle cells, and oocytes, and is released into the
usually less than 6 months. [13,14] surrounding extracellular space. The half-life of HA is three
days or less. [4]
Histopathologically, bovine collagen fibers are much thicker
than human collagen, have a homogeneous appearance Injections of HA are used for correction the wrinkles of the
nearly devoid of spaces between them, with fewer face, for soft tissue augmentation, and for filling all types of
fibroblasts, and fail to refract polarized light. Skin tests are defects. HA has become the most popular skin filler agent,
required before the injection of bovine collagen products. and reached a high patient satisfaction with a low incidence
Rare hypersensitive reactions, including foreign body of serious complications. The highly charged nature of HA
Plast Aesthet Res || Vol 3 || Mar 23, 2016 93