In mid-2003, LED-based light systems Omnilux™ were granted FDA clearance for acne and vascular and pigmented lesions. The company has more recently enlarged their scope with the development of a 633 nm visible red LED array, a minimally invasive skin rejuvenation system for anti-aging.
Minimally-invasive skin rejuvenation and its photobiological basics
The use of high levels of thermal damage associated with lasers and IPLs may not necessarily be required to regenerate skin. Given that the dermal cellular components are functioning normally it is logical that through the correct LED array, the bodies own cellular mechanisms can halt or reverse the signs of aging.
Recent studies have applied sophisticated photobiological principles to the treatment of photo-aging. Matching wavelengths with specific cellular targets have produced significantly better patient satisfaction in treatments which look at using optimal or combined wavelengths, to achieve the desired photoresponse.
Finding the Right Wavelength
Research into light therapy stems back to the 19th
century, the Italian scientist Fubini demonstrated that
red light had a specific effect on
mitochondria, increasing their
metabolic rate. The intracellular
specificity of red light on
organelles has been more recently
corroborated, in work from a number
of clinicians and researchers.
When this peer reviewed evidence
is taken into consideration, the
visible red spectral area around
633 nm seems the most effective
to stimulate dermal cells and activate
the cascade of events required to achieve reorganization
and tightening of the skins supportive matrix
and modulate the activity of the key cell in the dermis,
the fibroblast.
Inflammation: a ‘necessary evil’
Inflammation is key in non-ablative skin rejuvenation,
including minimally invasive red LED phototherapy.
The phases of wound healing and the cells
involved must be understood in order to appreciate the
important role of inflammation in these processes. In
the inflammatory phase, leukocytes peak, monocytes
transform into phagocytes and mast cells peak and
degranulate. This response initiates the migration of
more macrophage cells and fibroblasts to the target
stimulated by chemotactic signals from pre-existing
fibroblasts, leukocytes and macrophages.
At the start of the proliferation phase macrophages
gradually decrease and the number of fibroblasts peak
then start to drop off. At the end of the proliferation
phase two transitional events occur: the differentiation
of active fibroblasts into myofibroblasts and the de-differentiation
of active fibroblasts into dormant fibrocytes.
The role of the myofibroblasts, is to position
themselves on collagen fibers and exert a longitudinal
force on them, tightening and aligning them.
Red light at 633 nm has been shown to make mast
cells preferentially degranulate. Mast cells are present
in the dermis, located near blood vessels. The stimulation
given by their fast-acting proallergenic granules is
seen by the surrounding tissue as inflammation, so the
wound healing process is triggered without any thermal
damage.
This process is assisted by the continuous wave
633 nm light from the OmniLux Revive head, which
penetrates far into the target dermis to involve not
only the superficial and fine reticular dermis, but into
the mid and deep reticular dermis.
The first law of photobiology clearly states that
without any absorption there can be no reaction. With
the depth of penetration and absorption obtained with
photons at 633 nm there is absorption in all skin cells
at all levels, including blood vessel endothelial cells
and erythrocytes.
The inflammatory response from 633 nm is a controlled
short-lived phase, which transcends through to
the proliferation phase, together with the creation of
neovascularization and the increase of local blood and
lymphatic vessel flow. Lymphatic drainage is important
in transporting leukocytes and lymphocytes into
the target area and maintaining homeostasis of the
treated skin. An increased blood supply raises the oxygen
tension in the target area, creating cellular gradients
and ensuring that the connection between the
papillary dermis and the basement membrane of the
dermal-epidermal junction (DEJ) and the basement
membrane is supported.
Fibroblasts are essential in achieving the desired
effect in the dermis during the second and third phases
following the inflammatory reaction caused by photomediated
mast cell degranulation. The fibroblast is
multifunctional, not only synthesizing collagen and
elastin, but also regulating the homeostasis of the
ground substance and maintaining collagen fibers.
LED phototherapy offers a new and exciting treatment
modality, being non-invasive and safe with no
patient downtime. However, the key to successful light
therapy is the choice of the correct wavelength for photobiomodulation
and the continuous delivery of the
light in such a way as to maximize the light/photoacceptor
interaction.
And the future?
Work from Enwemeka, USA and the Trelles and
Dyson groups have shown that near infrared (IR) light
accelerates and strengthens the fibroblast-myofibroblast
transformation, causing faster degranulation of
mast cells when compared to 633 nm and has also been
proved to increase the chemotactic efficiency of both
leukocytes and macrophages.
Omnilux has recently developed an 830 nm head,
and preliminary studies in combination with the 633
nm head for minimally-invasive LED skin anti-aging
have been extremely effective with very high patient
satisfaction. The clinical results will be published in
detail in forthcoming articles.
-Excerpts from "The Photobiology of LED Phototherapy", by R. Glen Calderhead, MSc, DrMedSci, FRSM |
