Anders, J. J.

Barna, L.

Byrnes, K. R.

Ilev, I. K.

Smith, K.

Waynant, R. W.

Wu, X.

English

Engineering Conferences International

Page 1 of 2   11/23/2004 Light Activated Tissue Regeneration and Therapy August 22-27, 2004 Notes by Joan B. Martin MD  Please contact me with any corrections drjoanbmartin@yahoo.com or joan.b.martin@kp.org   810 NM LIGHT THERAPY IMPROVES AXONAL REGENERATION AND FUNCTIONAL RECOVERY FOLLOWING ACUTE SPINAL CORD INJURY Kimberly Byrnes, Georgetown University, USA • 11,000 new cases year • 55% between 16-20 y/o • 46% in the thoracic or lumbar region • Her interest is in the secondary injury o Demyelination o Axonal degeneration o Neuronal death o Cavitation o l\glial scarring o Inflammation  Cytokines  Cell invasion: neutrophils, macrophages and activated microglia o All of which exceed the injured area Treatments • Current o Anti-inflammatories: methylprednisolone o Removal of inhibitory factors o Growth factors  o Transplantation • Light therapy in low doses can have stimulatory effects o Increases DNA< RNA and protein synthesis o Improves axonal  • High dose > 10 J/cm2 can have the reverse, negative effect Hypothesis: transcutaneous application of light promotes axonal regeneration and functional reenervation of spinal cord neurons following transection in rats • Can light penetrate the spinal cord? o 810 nm, 150 mW laser, measure penetration: got 50% transmission through tissues, except higher in blood o Got 9 mw to spinal cord o In vivo measurements showed a peak of wavelength for deep penetration at 800-810 nm o Conclusion 810 nm light optimal to penetrate to spinal cord • Transected rat spinal cords • 810 nm 150 mW, 29 minutes, 57 seconds, 14 days = 1589 J/cm2 per day • Through a fiberoptic fiber that gave a homogeneous beam • Found increased axons distal to the lesion 5 wks post injury • Laser treated had 9 mm of growth past the lesion, control had 3 mm??? Page 2 of 2   11/23/2004 • 10% actual axonal regeneration in laser treated group Spinal cord injury and function • Laser treated were able to cross a ladder faster, but had the same number of “foot falls” • Conclusion: laser improved some locomotor abilities Most recent work: determine optimal parameters for light therapy: • Number of days: no difference between 14 and 2 • Improved if did 7 days of TX after the injury over the injury and then moved it distally • 24 hour delay in TX after injury does not seem to make a difference • Laser affects over 200 genes involved in spinal regeneration Summary • 6 hours post injury: neutrophils invade, cytokines? • 48 hr-14 days: macrophages and activated microglia invade + astrocytic activation leading to scar • Light alters gene expression after injury o Cytokines decrease o No decrease in neutrophil invasions o But significant decrease in macrophage and microglia invasion o Decreased inflammation and scarring o So improved axonal regeneration and functional recovery  

810 nm Light Therapy Improves Axonal Regeneration and Functional Recovery Following Acute Spinal Cord Injury

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1011&context=tissue_regen&type=additional

810 nm Light Therapy Improves Axonal Regeneration and Functional Recovery Following Acute Spinal Cord Injury

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Engineering Conferences International