Bridging peripheral nerves using a deacetyl chitin conduit combined with short-term electrical stimulation

Previous studies have demonstrated that deacetyl chitin conduit nerve bridging or electrical stimulation can effectively promote the regeneration of the injured peripheral nerve. We hypoth-esized that the combination of these two approaches could result in enhanced regeneration. Rats with right sciatic nerve injury were subjected to deacetyl chitin conduit bridging combined with electrical stimulation （0.1 ms, 3 V, 20 Hz, for 1 hour）. At 6 and 12 weeks after treatment, nerve conduction velocity, myelinated axon number, ifber diameter, axon diameter and the thickness of the myelin sheath in the stimulation group were better than in the non-stimulation group. The results indicate that deacetyl chitin conduit bridging combined with temporary electrical stimu-lation can promote peripheral nerve repair.

Long-term bone and lung consequences associated with hospital-acquired severe acute respiratory syndrome:a 15-year follow-up from a prospective cohort study

The most severe sequelae after rehabilitation from SARS are femoral head necrosis and pulmonary fibrosis. We performed a 15-year follow-up on the lung and bone conditions of SARS patients. We evaluated the recovery from lung damage and femoral head necrosis in an observational cohort study of SARS patients using pulmonary CT scans, hip joint MRI examinations, pulmonary function tests and hip joint function questionnaires. Eighty medical staff contracted SARS in 2003. Two patients died of SARS, and78 were enrolled in this study from August 2003 to March 2018. Seventy-one patients completed the 15-year follow-up. The percentage of pulmonary lesions on CT scans diminished from 2003(9.40 ± 7.83)% to 2004(3.20 ± 4.78)%(P < 0.001) and remained stable thereafter until 2018(4.60 ± 6.37)%. Between 2006 and 2018, the proportion of patients with interstitial changes who had improved pulmonary function was lower than that of patients without lesions, as demonstrated by the one-second ratio(FEV1/FVC%, t = 2.21, P = 0.04) and mid-flow of maximum expiration(FEF25%–75%, t = 2.76, P = 0.01). The volume of femoral head necrosis decreased significantly from 2003(38.83 ± 21.01)% to 2005(30.38 ± 20.23)%(P = 0.000 2), then declined slowly from 2005 to 2013(28.99 ± 20.59)% and plateaued until 2018(25.52 ± 15.51)%. Pulmonary interstitial damage and functional decline caused by SARS mostly recovered, with a greater extent of recovery within 2 years after rehabilitation. Femoral head necrosis induced by large doses of steroid pulse therapy in SARS patients was not progressive and was partially reversible.

Reply to “Can femoral head necrosis induced by steroid therapy in patients infected with coronaviruses be reversed?”

The authors reply:We deeply appreciated your interest in our research.In our study,the conclusion that femoral head necrosis induced by large doses of steroid pulse therapy in SARS patients was partially reversible was based on the results of the volume of femoral head necrosis on MRI combined with the ARCO stage.The volume of osteonecrosis decreased significantly from 2003(38.83%±21.01%)to 2005(30.38%±20.23%)(P=0.0002),then declined slowly from 2005 to 2013(28.99%±20.59%)and plateaued in 2018(25.52%±15.51%).The ARCO stages of 17 limbs in ten patients stabilized or improved during follow-up,while the stages of six limbs in four patients reflected deterioration.

Aligned fibrin/functionalized self-assembling peptide interpenetrating nanofiber hydrogel presenting multi-cues promotes peripheral nerve functional recovery

Nerve guidance conduits with hollow lumen fail to regenerate critical-sized peripheral nerve defects(15 mm in rats and 25 mm in humans),which can be improved by a beneficial intraluminal microenvironment.However,individual cues provided by intraluminal filling materials are inadequate to eliminate the functional gap between regenerated nerves and normal nerves.Herein,an aligned fibrin/functionalized self-assembling peptide(AFG/fSAP)interpenetrating nanofiber hydrogel that exerting synergistic topographical and biochemical cues for peripheral nerve regeneration is constructed via electrospinning and molecular self-assembly.The hydrogel possesses an aligned structure,high water content,appropriate mechanical properties and suitable biodegradation capabilities for nerve repair,which enhances the alignment and neurotrophin secretion of primary Schwann cells(SCs)in vitro,and successfully bridges a 15-mm sciatic nerve gap in rats in vivo.The rats transplanted with the AFG/fSAP hydrogel exhibit satisfactory morphological and functional recovery in myelinated nerve fibers and innervated muscles.The motor function recovery facilitated by the AFG/fSAP hydrogel is comparable with that of autografts.Moreover,the AFG/fSAP hydrogel upregulates the regeneration-associated gene expression and activates the PI3K/Akt and MAPK signaling pathways in the regenerated nerve.Altogether,the AFG/fSAP hydrogel represents a promising approach for peripheral nerve repair through an integration of structural guidance and biochemical stimulation.