Haematic derivatives

Haematic derivatives have rich potential to treat a wide range of ocular surface diseases such as neurotrophic dry eye, post-LASIK or post-keratoplasty dry eye and graft versus host disease (GVHD), among other potential ocular applications, according to Jesús Merayo-Lloves MD. Addressing a clinical research symposium on new drug-delivery methods at the XXXV Congress of the ESCRS in Lisbon, Dr Merayo-Lloves explained that platelet-rich plasma (PRP) derivatives work by supplying fundamental factors to maintain the integrity of the ocular surface. “Early studies and our own clinical experience to date have shown the effectiveness of plasma rich in growth factors (PRGF) in the management of patients with severe or moderate dry eye disease. However, it will probably prove of most benefit in patients with neurotrophic dry eye, dry eye post-LASIK or post keratoplasty and graft versus host disease (GVHD),” he said. Despite the widespread use of platelet preparations in medical applications, there is no consensus on the most appropriate preparation method, and growth factors concentration vary with different systems, said Dr Merayo-Lloves. GROWTH FACTORS More than 30 growth factors, which play an important role in tissue regeneration and wound healing, have already been identified in platelets, he said. Research by Anitua et al. led to these growth factors being combined with autologous proteins and biomaterials in a therapeutic formulation that they called plasma rich in growth factors (PRGF-Endoret). “The PRGF protocol is easy to use and we have successfully developed several different PRGF formulations: collyrium, fibrin clot and membrane. It can also be used as a scaffold for stem cell applications or as an amniotic membrane substitute,” he said. A key difference between PRGF and autologous serum is the ability of the former to suppress myofibroblasts, said Dr Merayo-Lloves. “In studies it was shown that the myofibroblasts disappear from corneal tissue or cell cultures when PRGF is present. This is important because myofibroblasts are known to play a major role in corneal haze and are also associated with problems of scarring in glaucoma and retinal surgery,” he said. Since the first trials in humans in 2009, PRGF has now been used to treat chemical burns, neurotrophic ulcers and dry eye after GVHD. For ease of use in the clinic, PRGF is now available in the form of an eye drop kit that is biologically stable for up to three months, said Dr Merayo-Lloves. “We tested the kit in 850 patients with moderate-to-severe dry eye associated with various pathologies that were not responding to traditional lubricants or anti-inflammatory treatments. The results were very promising in terms of the improvement of visual acuity and reduction in the severity of symptoms,” he concluded. Jesús Merayo-Lloves: merayo@fio.as