light and wound healing

LIGHT AND WOUND HEALING

By:Amin Talebi (MSc)

Shiraz University of Medical Science; Medical Physics Department

Outline

Why wound healing is important ?

Normal wound healing

History of the use of light in the wound healing

The optimum wavelength and incident dose

Mechanisms of action

Conclusion

References

Why wound healing is important ?

• Wound causes can be internal or external in origin

• Wounds of internal origin are mainly due to impaired

circulation, neuropathy or medical illness

• Wounds of external origin are due to an outside force or

trauma that causes open or closed wounds.

Why wound healing is important ?

• 382 million people have diabetes in 2013; by 2035 this will rise to 592

million

• Approximately 15 percent of diabetics will develop a foot ulcer at some

point. Foot ulcers are the most common wounds for this patient

population.

• According to statistics, diabetes is the number one reason for limb

amputation in the U.S.

Wound healing can be slowed when the patient is diabetic

• Blood Glucose Levels

• Poor Circulation

• Diabetic Neuropathy

• Immune System Deficiency

• Infection

Normal wound healing

There are four phases of normal wound healing

I. Vascular Response (Hemostasis)

II. Inflammatory Response (Inflammation)

III. The Proliferative Phase (Granulation, Epithelialization)

IV. Maturation Phase (Reconstruction phase)

Vascular Response (Hemostasis)

• Vasoconstriction – within seconds, regardless of the source of

injury, blood vessels constrict to stop bleeding and reduce

exposure to bacteria

• Platelets cluster together at the site of injury to form a ‘clot’

• Wound healing begins within minutes after tissue damage

Inflammatory Response (Inflammation)

• This is the body’s early defense system against microbial

invasion

• Neutrophils and Macrophages ingest injurious agents,

thereby protecting against bacterial invasion.

• Disorders that lead to reduced numbers of phagocytic cells

slow the inflammatory process and make the person more

prone to infection

The Proliferative Phase (Granulation, Epithelialization)

• Granulation occurs. Collagen, capillaries and cells begin to fill the wound space with new connective tissue.

• Epithelialization occurs as epithelial cells migrate from surrounding skin. This tissue is very fragile

Maturation Phase (Reconstruction phase)

• Remodeling of the scar continues for approximately 1 year

• Scar tissue regains about two thirds of its original strength

• Scar tissue is never as strong as the original tissue it replaces

Normal wound healing

History of the use of light in the wound healing

• light therapy is one of the oldest therapeutic methods used by humans

• historically as solar therapy by Egyptians, later as UV therapy for which Nils Finsen won the Nobel prize in 1904

• The use of lasers and LEDs as light sources was the next step in the technological development of light therapy, which is now applied to many thousands of people worldwide each day

History of the use of light in the wound healing

• LASER is an acronym for Light Amplification by the Stimulated

Emission of Radiation.

• During the 1960s and 1970s, lasers were regarded as destructive .

• those lasers using photothermal and ablative properties are used

routinely to cut and destroy tissue. This is known as laser surgery.

• The therapeutic properties of relatively low intensity, athermic laser

irradiation were then recognised. This is referred to as laser therapy.

History of the use of light in the wound healing

• In 1967 Endre Mester in Semmelweis University, Budapest, Hungary wanted to test if laser radiation might cause cancer in mice.

• He shaved the dorsal hair, divided them into two groups and gave a laser treatment with a low powered ruby laser (694-nm) to one group.

• They did not get cancer

• The hair on the treated group grew back more quickly than the untreated group

• The use of low levels of visible or near infrared light for

reducing pain, inflammation and edema, promoting healing

of wounds, deeper tissues and nerves has been known for

almost forty years since the invention of lasers.

LASER vs LED

• LASER light is:

coherent (all wavelengths are produced in phase)

monochromatic (of single colour or wavelength)

Collimated (produces a close parallel beam)

LASER vs LED

• LED light is:

• Noncoherent

• Polychromatic

• with broader line width

Schematic representation of the main areas of application of LLLT

• Differences exist in the delivery of LLLT.

• Variables include laser type and wavelength, the use of a

single wavelength or a combination of wavelengths,

irradiance or dosage, beam divergence, spot size and

duration of treatment

• The He-Ne laser was the first laser available and is reported to have beneficial effects in both wound healing and dentistry.

• The He-Ne laser has the advantage that it emits red light, which is visible and therefore the blink reflex protects the eye from it.

• The GaAs and GaAlAs laser have been most commonly used for the treatment of pain and inflammation.

• These lasers have the disadvantage that their light is invisible and therefore eye protection is required.

The optimum wavelength and incident dose

• The study was performed using 532,633,810, and 980 nm diode

lasers

• Incident doses of 5, 10, 20, and 30 J/cm2 .

• The wound healing on control rats with diabetes was slower than on control rats without diabetes.

• LLLT at appropriate treatment parameters can enhance the wound healing on diabetic rats

• Result showed that the optimum wavelength and incident dose was 633 nm and l0 J/cm .

• irradiation of visible laser light was better than invisible laser light in the treatment of wound healing on diabetic rats.

• The reason for the effective acceleration of wound healing on diabetic rats using low-power lasers was that perhaps the absorption of laser light with specific wavelength by target tissue resulted in the enhancement of fibroblast proliferation and the promotion of collagen metabolism and granulation tissue formation in the diabetic wound

Laser and LED phototherapies on angiogenesis

• One very important phenomena involved on the formation of the granulation tissue is angiogenesis.

• It is essential for the supply of oxygen and nutrients for the healing wound allowing both cell proliferation and deposition of the collagen matrix

• There are many studies on the use of laser light aiming to positively stimulating the healing process, being the stimuli to angiogenesis one of the most frequently reported.

• Previous studies have shown that, similar to laser light, the use of LEDs presents an important effect on both angiogenesis and vascularity.

Laser and LED phototherapies on angiogenesis

• There is an increase on angiogenesis on green LED (p<0.001), red LED (p00.001), IR laser (p00.012) and red laser (p00.034) groups.

• No difference between the blue LED group and the control.

• The comparison among all illuminated groups showed a significant increase on angiogenesis on green LED and red LED in relation to the red laser group

Laser and LED phototherapies on angiogenesis

• the most evident effect on endothelial cells seen when doses of 1.05 or 2.1 J/cm2 were used.

• the effects of both light sources are dependent on both wavelength and energy density rather than on the coherence.

Laser and LED phototherapies on angiogenesis

• in this study λ530+20 nm LED light group showed the most increased angiogenesis.

• Result showed that not only red LEDs but also green LEDs can be a new powerful therapeutic strategy for wound healing

Multiwavelength Light Therapy

• To study the efficacy of multiwavelength light therapy in the treatment of pressure ulcers in subjects with spinal cord disorders.

• Thirty-five subjects with spinal cord injury, with 64 pressure ulcers (stage 2, n=55; stage 3, n=8; stage 4, n=1), were randomized into treatment and control groups.

• Treatment group received 14 sessions of multiwavelength light therapy, with 46 probes of different wavelengths from a gallium-aluminum-arsenide laser source, 3 times a week.

• Energy used was 4.5J/cm2.

• Ulcers in the control group received sham treatment.

Characteristics of Multiwavelength Light Source

The central 820nm laser source was surrounded by 45 supraluminous diodes of different wavelengths.

Results

• No significant difference in healing between the treatment and control groups.

• Multiwavelength light therapy from a gallium- aluminum-arsenide laser source did not influence overall healing pressure ulcers.

DNA damage after phototherapy

• This study aimed to determine the effects of phototherapy induced DNA damage.

• human skin fibroblast cells.

• Irradiated twice once at 30 min and again at 72 h with 5 or 16 J/cm2.

• using a diode laser at 636 nm.

Results

• At both 1 and 24 h, wounded cells irradiated with 5 J/cm2 showed insignificant DNA damage compared to control cells.

• irradiation with 16 J/cm2 showed significant damage.

• 24 h post-irradiation these cells showed a significant decrease in damage compared to cells left to incubate for 1 h.

Mechanism of action of LLLT

• One theory regarding that the laser is capable of influencing photoreceptors in the cells.

• This mechanism is referred to as photobiology or biostimulation.

• It has been reported that photobiostimulation occurs via the electron transport chain enzymes in mitochondria,

Mechanism of action of LLLT

• The biostimulating effect of LLLT results in an increase in microcirculation, higher production rates for ATP, RNA, and DNA synthesis, thus improving cellular oxygenation, nutrition, and regeneration and an enhanced mitochondrial electron transport system.

Mechanism of action of LLLT

• The magnitude of the laser biostimulation effect depends on

the wavelength used

the physiological state of the cell at the moment of irradiation

Biphasic dose response of LLLT

• LLLT delivered at low doses may produce a better result when compared to the same wavelength delivered at high doses.

• Weak stimuli slightly accelerate vital activity and stronger stimuli raise it further

• but when a peak is reached, then stronger stimuli suppress it, until a negative response is finally achieved.

Idealized biphasic dose response curve

Biphasic dose response

• The biphasic curve will be helpful to identify the sufficient energy level that will be applied to get maximum biostimulation.

• If insufficient energy is applied then there will be no response (because the minimum threshold has not been met).

• If more energy is applied, then a threshold is crossed and biostimulation disappears and is replaced by bioinhibition instead

Conclusion

• Although the usefulness of phototherapy in wound healing is

still controversial, it has become a popular treatment

modality in many clinics.

• As this therapy has few contraindications and no reported

side effects, it could be considered as a potentially useful

treatment option if shown to be effective

Conclusion

• There appear to be many anecdotal claims that phototherapy stimulates wound healing but the question arises as to whether sufficient scientific evidence exists to justify its routine use in wound care.

References

• MARIUSZ CHYCZEWSKI, PIOTR HOLAK , MAREK JAŁYŃSKI , ALEKSANDER

KASPROWICZ , TADEUSZ ROTKIEWICZ1, AND ANNA MIKOŁAJCZYK1. EFFECT OF LASER BIOSTIMULATION ON THE HEALING OF CUTANEOUS SURGICAL WOUNDS IN PIGS.

FAROUKA.H. AL-WAIBAN, M.Sc., Ph.D, XING YANG ZHANG, M.D., and

BERNARD L. ANDRES. MT(AMT). Low-Level LaserT herapyE nhancesW oundH ealingi n

DiabeticR ats:A Comparisono f Different Lasers. Photomedicine and Laser Surgery

Volume 25, Number 2,2007

Michael R Hamblin a,b,c,* and Tatiana N Demidova. Mechanisms of Low Level Light Therapy.

Adel J. Hussein1, Abdalbari A. Alfars2, Mohsin A. J. Falih2, Al-Nawar A. Hassan2. Effects of a low level laser on the acceleration of wound healing in rabbits. North American Journal of Medical Sciences 2011 April, Volume 3. No. 4.

Thanks for your attention