Delivery of therapeutics to posterior eye segment:cell-encapsulating systems

Drug delivery to the posterior segment of the eye, especially the retina, faces the unique challenges of various anatomical and physiological barriers. Invasive intravitreal injection is currently the mainstream clinical approach to posterior eye diseases such as age-related macular degeneration, diabetic retinopathy, uveitis, and cytomegalovirus retinitis. Repeated injections could be complicated by endophthalmitis, intra- ocular pressure elevation, retinal vascular occlusion, and ret- inal detachment, let alone the psychological and economical burdens suffered by patients （Schwartz et al., 2014）. In view of this, several extended release drug delivery systems have been devised and the idea of encapsulated-cell technology （ECT） has gained popularity in recent decades since its first proposal in the 1960s.

Neurovascular unit in diabetic retinopathy:pathophysiological roles and potential therapeutical targets

Diabetic retinopathy(DR),one of the common complications of diabetes,is the leading cause of visual loss in working-age individuals in many industrialized countries.It has been traditionally regarded as a purely microvascular disease in the retina.However,an increasing number of studies have shown that DR is a complex neurovascular disorder that affects not only vascular structure but also neural tissue of the retina.Deterioration of neural retina could precede microvascular abnormalities in the DR,leading to microvascular changes.Furthermore,disruption of interactions among neurons,vascular cells,glia and local immune cells,which collectively form the neurovascular unit,is considered to be associated with the progression of DR early on in the disease.Therefore,it makes sense to develop new therapeutic strategies to prevent or reverse retinal neurodegeneration,neuroinflammation and impaired cell-cell interactions of the neurovascular unit in early stage DR.Here,we present current perspectives on the pathophysiology of DR as a neurovascular disease,especially at the early stage.Potential novel treatments for preventing or reversing neurovascular injuries in DR are discussed as well.

Neurovascular unit in diabetic retinopathy:pathophysiological roles and potential therapeutical targets

Diabetic retinopathy(DR),one of the common complications of diabetes,is the leading cause of visual loss in working-age individuals in many industrialized countries.It has been traditionally regarded as a purely microvascular disease in the retina.However,an increasing number of studies have shown that DR is a complex neurovascular disorder that affects not only vascular structure but also neural tissue of the retina.Deterioration of neural retina could precede microvascular abnormalities in the DR,leading to microvascular changes.Furthermore,disruption of interactions among neurons,vascular cells,glia and local immune cells,which collectively form the neurovascular unit,is considered to be associated with the progression of DR early on in the disease.Therefore,it makes sense to develop new therapeutic strategies to prevent or reverse retinal neurodegeneration,neuroinflammation and impaired cell-cell interactions of the neurovascular unit in early stage DR.Here,we present current perspectives on the pathophysiology of DR as a neurovascular disease,especially at the early stage.Potential novel treatments for preventing or reversing neurovascular injuries in DR are discussed as well.