Safety aspects of longitudinal administration of IGF-I/IGFBP-3 complex in neonatal mice

The progress of prophylactic treatment in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a retinal vascular disorder frequently found in premature infants. Different therapeutic strategies have been developed to treat ROP. However, there are still many children with ROP suffering by severe limitations in vision or even blindness. Recently, ROP has been suggested to be caused by abnormal development of the retinal vasculature, but not simply resulted by retinal neovascularization which takes about 4 to 6wk after birth in premature infants. Thus, instead of focusing on how to reduce retinal neovascularization, understanding the pathological changes and mechanisms that occur prior to retinal neovascularization is meaningful, which may lead to identify novel target(s) for the development of novel strategy to promote the healthy growth of retinal blood vessels rather than passively waiting for the appearance of retinal neovascularization and removing it by force. In this review, we discussed recent studies about, 1) the pathogenesis prior to retinal neovascularization in oxygen-induced retinopathy (OIR; a ROP in animal model) and in premature infants with ROP; 2) the preclinical and clinical research on preventive treatment of early OIR and ROP. We will not only highlight the importance of the mechanisms and signalling pathways in regulating early stage of ROP but also will provide guidance for actively exploring novel mechanisms and discovering novel treatments for early phase OIR and ROP prior to retinal neovascularization in the future.

Effect of insulin-like growth factor-I during the early postnatal period in intrauterine growth-restricted rats

BACKGROUND

Insulin-like growth factor-I (IGF-I) is essential for perinatal growth and development; low serum IGF-I has been observed during intrauterine growth restriction (IUGR). We investigated the effects of recombinant human (rh) IGF-I in IUGR rats during the early postnatal period.

METHODS

Intrauterine growth restriction was induced by bilateral uterine artery ligation in pregnant rats. IUGR pups were divided into two groups injected daily with rhIGF-I (2 mg/kg; IUGR/IGF-I, n = 16) or saline (IUGR/physiologic saline solution (PSS), n = 16) from postnatal day (PND) 7 to 13. Maternal sham-operated pups injected with saline were used as controls (control, n = 16). Serum IGF-I and IGF binding proteins (IGFBP) 3 and 5 were measured on PND25. The expression of Igf-i, IGF-I receptor (Igf-ir), Igfbp3, and 5 mRNA in the liver and brain was measured using real-time polymerase chain reaction on PND25. Immunohistochemical staining of the liver for IGF expression was performed.

RESULTS

Mean bodyweight on PND3 and PND25 in the IUGR pups (IUGR/IGF-I and IUGR/PSS) was significantly lower than that of the control pups. Serum IGF-I and hepatic Igf-ir mRNA in the IUGR pups were significantly lower than those in the control pups. In the IUGR/IGF-I group, hepatic Igfbp3 mRNA and liver immunohistochemical staining were increased. In the IUGR/PSS and control pups, there were no significant differences between these two groups in serum IGFBP3 and IGFBP5, hepatic Igf-i and Igfbp-5 mRNA, or brain Igf mRNA.

CONCLUSIONS

No benefits on body and brain weight gain but an effective increase in hepatic IGFBP-3 was observed after treatment with 2 mg/kg rhIGF-I during the early postnatal period.

Dietary proteins and IGF I levels in preterm infants: determinants of growth, body composition, and neurodevelopment

It has been demonstrated that a high-protein diet in preterm born infants during the first weeks of life may enable a growth rate equal to that seen in utero and may also result in a better long-term neurodevelopmental outcome. This diet may limit immediate postnatal growth retardation and may hence lower the risk of increased fat deposition after birth leading to the metabolic syndrome in later life. Insulin-like growth factor I (IGF I) has proven to play an important role in early postnatal growth of preterm infants, but also seems to have a persisting influence on body composition in childhood. Furthermore, increased IGF I concentrations in preterm infants have been associated with improved neurodevelopmental outcome. This review will elaborate on the role of dietary proteins and IGF I on growth, body composition, and neurodevelopment of preterm infants. Possible causal pathways will be explored and areas for future research will be proposed.

Prediction of severe retinopathy of prematurity using the WINROP algorithm in a birth cohort in South East Scotland

PURPOSE

We tested the ability of the 'Weight, IGF-1, Neonatal Retinopathy of Prematurity (WINROP)' clinical algorithm to detect preterm infants at risk of severe Retinopathy of Prematurity (ROP) in a birth cohort in the South East of Scotland. In particular, we asked the question: 'are weekly weight measurements essential when using the WINROP algorithm?'

STUDY DESIGN

This was a retrospective cohort study. Anonymised clinical data were uploaded to the online WINROP site, and infants at risk of developing severe ROP were identified. The results using WINROP were compared with the actual ROP screening outcomes. Infants with incomplete weight data were included in the whole group, but were excluded from a subgroup analysis of infants with complete weight data. In addition, data were manipulated to test whether missing weight data points in the early neonatal period would lead to loss of sensitivity of the algorithm.

RESULTS

The WINROP algorithm had 73% sensitivity for detecting infants at risk of severe ROP when all infants were included and 87% when the complete weight data subgroup was analysed. Manipulation of data from the complete weight data subgroup demonstrated that one or two missing weight data points in the early postnatal period lead to loss of sensitivity performance by WINROP.

IMPLICATIONS

The WINROP program offers a non-invasive method of identifying infants at high risk of severe ROP and also identifying those not at risk. However, for WINROP to function optimally, it has to be used as recommended and designed, namely weekly body weight measurements are required.