Circular RNA PTP4A2 regulates microglial polarization through STAT3 to promote neuroinflammation in ischemic stroke

OBJECTIVE

Microglial polarization plays a critical role in neuroinflammation and may be a potential therapeutic target for ischemic stroke. This study was to explore the role and underlying molecular mechanism of Circular RNA PTP4A2 (circPTP4A2) in microglial polarization after ischemic stroke.

METHODS

C57BL/6J mice underwent transient middle cerebral artery occlusion (tMCAO), while primary mouse microglia and BV2 microglial cells experienced oxygen glucose deprivation/reperfusion (OGD/R) to mimic ischemic conditions. CircPTP4A2 shRNA lentivirus and Colivelin were used to knock down circPTP4A2 and upregulate signal transducer and activator of transcription 3 (STAT3) phosphorylation, respectively. Microglial polarization was assessed using immunofluorescence staining and Western blot. RNA pull-down and RNA binding protein immunoprecipitation (RIP) were applied to detect the binding between circPTP4A2 and STAT3.

RESULTS

The levels of circPTP4A2 were significantly increased in plasma and peri-infarct cortex in tMCAO mice. CircPTP4A2 knockdown reduced infarct volume, increased cortical cerebral blood flow (CBF), and attenuated neurological deficits. It also decreased pro-inflammatory factors levels in peri-infarct cortex and plasma, and increased anti-inflammatory factors concentrations 24 h post-stroke. In addition, circPTP4A2 knockdown suppressed M1 microglial polarization and promoted M2 microglial polarization in both tMCAO mice and OGD/R-induced BV2 microglial cells. Moreover, circPTP4A2 knockdown inhibited the phosphorylation of STAT3 induced by oxygen-glucose deprivation. In contrast, increased phosphorylation of STAT3 partly counteracted the effects of circPTP4A2 knockdown. RNA pull-down and RIP assays further certified the binding between circPTP4A2 and STAT3.

CONCLUSION

These results revealed regulatory mechanisms of circPTP4A2 that stimulated neuroinflammation by driving STAT3-dependent microglial polarization in ischemic brain injury. CircPTP4A2 knockdown reduced cerebral ischemic injury and promoted microglial M2 polarization, which could be a novel therapeutic target for ischemic stroke.

Remote limb ischemic postconditioning inhibits microglia pyroptosis by modulating HGF after acute ischemia stroke

The repetitive inflation-deflation of a blood pressure cuff on a limb is known as remote limb ischemic postconditioning (RIPostC). It prevents brain damage induced by acute ischemia stroke (AIS). Pyroptosis, executed by the pore-forming protein gasdermin D (GSDMD), is a type of regulated cell death triggered by proinflammatory signals. It contributes to the pathogenesis of ischemic brain injury. However, the effects of RIPostC on pyroptosis following AIS remain largely unknown. In our study, linear correlation analysis confirmed that serum GSDMD levels in AIS patients upon admission were positively correlated with NIHSS scores. RIPostC treatment significantly reduced GSDMD level compared with patients without RIPostC at 3 days post-treatment. Besides, middle cerebral artery occlusion (MCAO) surgery was performed on C57BL/6 male mice and RIPostC was induced immediately after MCAO. We found that RIPostC suppressed the activation of NLRP3 inflammasome to reduce the maturation of GSDMD, leading to decreased pyroptosis in microglia after AIS. Hepatocyte growth factor (HGF) was identified using the high throughput screening. Importantly, HGF siRNA, exogenous HGF, and ISG15 siRNA were used to reveal that HGF/ISG15 is a possible mechanism of RIPostC regulation in vivo and in vitro.

Effects of NGS-based PGT-a for idiopathic recurrent pregnancy loss and implantation failure: a retrospective cohort study

To clarify the effect of next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) combined with trophectoderm (TE) biopsy on the pregnancy outcomes of idiopathic recurrent pregnancy loss (iRPL) and idiopathic recurrent implantation failure (iRIF), we conducted a retrospective cohort study of 212 iRPL couples and 66 iRIF couples who underwent PGT-A or conventional in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment. The implantation rate (IR) per transfer (64.2%), clinical pregnancy rate (CPR) per transfer (57.5%), and live birth rate (LBR) per transfer (45%) of iRPL couples of the PGT-A treatment group were significantly higher (p < 0.05) than those of the conventional IVF/ICSI group (IR per transfer,38.2%; CPR per transfer,33.3%; LBR per transfer, 28.4%), whereas the pregnancy loss rate (PLR) per transfer was similar between the two groups. These effects were also significant (p < 0.05) in iRPL couples with advanced maternal age (AMA, ≥35 years), whereas no significant differences were found in clinical outcomes between the PGT-A and conventional IVF/ICSI groups in younger iRPL couples (<35 years). The cumulative clinical outcomes of iRPL couples were comparable between the PGT-A and conventional IVF/ICSI groups. No significant differences were found in any clinical outcomes between the PGT-A and conventional IVF/ICSI groups for young or AMA couples with iRIF. In conclusion, NGS-based PGT-A involving TE biopsy may be useful for iRPL women to shorten the time to pregnancy and reduce their physical and psychological burden, especially for iRPL women with AMA; however, couples with iRIF may not benefit from PGT-A treatment. Considering the small sample size of the iRIF group, further investigations with a larger sample size are needed to verify our findings.

Silva Classification System for HPV-Related EAC of Stage I ∼ IIIc1p Cervical Adenocarcinoma and Its Effect on Prognosis and Survival

PURPOSE/OBJECTIVE(S)

The proportion of adenocarcinoma in cervical cancer gradually increased and presented a younger trend. The previous pathological classification of cervical adenocarcinoma is difficult to provide reference for clinical treatment. In recent years, Silva classification, a new pathologic system for cervical adenocarcinoma, has been confirmed to be suitable for HPV-associated adenocarcinoma (HPVA), and has shown certain clinical application value in subsequent studies. Therefore, this study will retrospectively analyze the distribution of Silva typing system in patients with HPVA under standard treatment mode and its relationship with prognosis and survival.

MATERIALS/METHODS

From January 2010 to September 2021, 124 cervical adenocarcinoma patients with HPVA were retrospectively included, who underwent radical resection of cervical cancer. The HE staining sections of the patients were divided into SilvaA, SilvaB, and SilvaC types according to the Silva typing system. Kaplan-Meier calculation was used for single-factor analysis, and COX stepwise regression model was used for multi-factor analysis.

RESULTS

Of the 124 patients with HPVA who could be graded according to the Silva system, 16 (12.9%, 16/124) were SilvaA, 27 (21.7%, 27/124) SilvaB, and 81 (65.4%, 81/124) SilvaC. In Silva classification, FIGO staging of Silva A and B was stage I. And FIGO staging of Silva C was more significantly later than the staging of Silva A and B. All lymph node metastases and paruterine infiltrates were found only in Silva C. In addition, the patients with Silva C large mass accounted for a higher proportion (41.7%). SilvaA type cervical adenocarcinoma patients were in a survival state by the end of follow-up. Among Silva B, 3 patients died due to tumor, and the 5-year OS rate were 91.3%. Among SilvaC, 15 patients died due to tumor, and the 5-year OS rate were 76.5%. FIGO stage and lymph node invasion were the influencing factors for survival and prognosis of Silva classification (P <0.05). FIGO stage, tumor size, lymph node invasion, and paralegal invasion were the influencing factors for survival and prognosis of SilvaC patients (P <0.05).

CONCLUSION

Silva model classification system combined with clinicopathological features has certain clinical value for the prognostic guidance of HPVA patients. Among Silva classification, SilvaC had the worst prognosis. Late FIGO stage, lymph node metastasis, and paralegal infiltration are the influencing factors for survival and prognosis of SilvaC type.

Increased plasma levels of circPTP4A2 and circTLK2 are associated with stroke injury

OBJECTIVE

Accumulating studies have shown that circulating circular RNAs (circRNAs) represent novel biomarkers for many human diseases. We investigated whether plasma circPTP4A2 and circTLK2 levels are associated with stroke severity, infarct volume, stroke etiology, and functional outcome in acute ischemic stroke (AIS) patients.

METHODS

We applied quantitative real-time PCR (qPCR) to measure plasma circPTP4A2 and circTLK2 levels of 236 AIS patients within 72 h of symptoms onset and 136 healthy controls. We further assessed the National Institutes of Health Stroke Scale (NIHSS), infarct size, the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification and the 90-day modified Rankin scale (mRS) for each patient.

RESULTS

At admission, plasma circPTP4A2 and circTLK2 levels in patients with moderate to severe stroke were significantly higher compared to those with mild stroke. Logistic regression and receiver-operating characteristic (ROC) curve analyses indicated that they might function as predictive biomarkers for moderate to severe stroke. We also observed a medium positive correlation between these two circRNAs and NIHSS. Plasma circPTP4A2 and circTLK2 levels were slight positively correlated with cerebral infarct volume only in anterior circulation infarction (ACI) patients. Levels of both circPTP4A2 and circTLK2 were closely related with large artery atherosclerosis (LAA) stroke. Moreover, changes within 7 days after admission in circPTP4A2 and circTLK2 were able to predict unfavorable clinical outcome 90 days after AIS.

INTERPRETATION

These results demonstrate that plasma circPTP4A2 and circTLK2 strongly correlated with severity, subtypes and prognosis of AIS, and they could serve as promising biomarkers.

Factors of Dental Care Utilization in Foreign-Born Older Chinese Americans

Good oral health is essential for healthy aging. Regular dental care utilization is instrumental to good oral health. Older immigrants tend to experience poorer oral health and less dental care use as compared with their native-born counterparts in the host country. Older immigrants are particularly vulnerable to interrupted or lost social ties and acculturation challenges after immigration to a new country. This study examined whether and to what extent social relations, acculturation, and perceived oral health needs are associated with dental care utilization in foreign-born older Chinese Americans. Data came from the Population Study of Chinese Elderly in Chicago, which were collected between 2017 and 2019 (N = 3,000). Dental care utilization was dichotomized into "yes" versus "no" in the past 2 y. Social relations were measured by positive and negative relations with spouse, family, and friends. Acculturation was measured by length of stay, behavioral acculturation, and residence in Chinatown. Perceived oral health needs were measured by the presence of problems related to teeth, gums, or bleeding. As guided by the Andersen model, separate logistic regression models were used to investigate factors of dental care utilization. An overall 23.1% reported dental care utilization. Individuals with no negative relations with spouse, family, and friends were 31%, 36%, and 38% less likely to visit a dentist, respectively. Individuals with higher levels of behavioral acculturation were 4% more likely to visit a dentist; individuals living in Chinatown were 45% less likely; and individuals with perceived oral health needs were 2.5 times more likely. Findings illustrate the importance of understanding social relations, immigration-related factors, and perceived oral health needs in dental care utilization in older immigrants.

[Applied anatomical study and clinical application of the caudate lobe boundary and ductal system of the liver]

Objective: To explore the relationship between the hepatic caudate lobe boundary and the ductal system so as to guide the identification of the anatomical relationship during liver surgery. Methods: The specific parts were observed and the liver parenchyma was removed according to 41 cadaveric liver autopsy specimens. The critical relationship between the hepatic caudate lobe and other ducts was observed to explore the reticular duct structure. Results: The plane formed by the hepatic hilar plate and Arantius ligament served as the boundary between the caudate lobe and other hepatic lobes. The caudate lobe hepatic portal vein was composed of numerous small branches from its left and right branches. The portal vein adjacent to the vena cava was mainly derived from the left branch, and to a lesser extent from the right branch. Blood was drained straight from the caudate lobe vein into the inferior vena cava via the short hepatic vein. There were three or four bile duct branches in the caudate lobe. The main source of arterial blood flow were the left and right branches of the hepatic artery. An avascular zone of loose connective tissue was found between the caudate lobe and the retrohepatic inferior vena cava. Conclusion: The hepatic caudate lobe is an independent lobe. During hepatic caudate lobe surgery, the plane formed by the hepatic hilar plate and Arantius ligament can serve as the boundary between the caudate lobe and other hepatic lobes and be used for anatomical site identification. The duct system of the caudate lobe's is complicated, but it also has its own distinct regularity.

Retrospective analysis of risk factors for bone metastasis in newly diagnosed prostate cancer patients

OBJECTIVE

The aim of the study was to analyze the clinical data of newly diagnosed prostate cancer (PCa) patients with bone metastasis and to explore the relevant risk factors.

PATIENTS AND METHODS

The clinical data of 251 patients with PCa, who were initially diagnosed in our hospital from February 2015 to October 2021, were retrospectively analyzed. According to the whole-body bone scan results, patients were divided into the bone metastasis group (n = 66) and the non-bone metastasis group (n = 185). The patient's age, total prostate-specific antigen (TPSA), free PSA (fPSA), prostate volume, alkaline phosphatase (ALP), Gleason score, erythrocyte sedimentation rate (ESR), and pelvic lymph node metastasis were collected. Univariate correlation and multivariate regression analyses, together with receiver operating characteristic curve, were used to analyze PCa bone metastasis-related factors.

RESULTS

The incidence of bone metastasis in newly diagnosed PCa was about 26.29% (66/251). Among them, the incidence of pelvic metastasis was the highest, at 78.78% (52/251), and multiple bone metastases were significantly higher than single bone metastasis (80.31% vs. 19.69%). Univariate correlation analysis indicated that age, Gleason score, ESR, TPSA, ALP, fPSA/PSA, capsular infiltration, and pelvic lymph node metastasis (p < 0.05) were highly correlated with PCa bone metastasis. Multivariate Logistic regression analysis showed that TPSA (95% CI: 0.977-1.284, p = 0.007), ALP (95% CI: 1.008-1.080, p = 0.016), Gleasons core (95% CI: 2.110-82.349, p = 0.006), ESR (95% CI: 1.062-1.104, p = 0.003), and pelvic lymph node metastasis (95% CI: 1.537--33.239, p = 0.012) were independent risk factors for bone metastasis of PCa. The cut-off values for TPSA, ALP, Gleason score, and ESR were 33.78 ng/ml, 73.65 U/L, 7.5, and 23.5 mm/h, respectively. Additionally, the respective sensitivities for TPSA, ALP, Gleason score, and ESR were 81.8%, 75.8%, 68.2% and 77.3%, and the respective specificities was 90.3%, 98.9%, 98.4%, and 74.6%.

CONCLUSIONS

TPSA, ALP, Gleason score, ESR and pelvic lymph node metastasis are independent risk factors for bone metastasis of PCa.

A validation study of a continuous automatic measurement of the mechanical power in ARDS patients

The mechanical power (MP) is the energy delivered into the respiratory system over time. It can be computed as a direct measurement of the inspiratory area of the airway pressure and volume loop during the respiratory cycle or calculated by "power equations". The absence of a bedside computation limited its widespread use. Recently, it has been developed an automatic monitoring system inside of a mechanical ventilator.

PURPOSE

Our aim was to investigate the repeatability and the accuracy of the measured MP at different PEEP values and tidal volume compared with the calculated MP.

MATERIAL AND METHODS

MP was measured and calculated in sedated and paralyzed ARDS patients at low and high tidal volume, at 5-10-15 cmH₂O of PEEP both in volume and pressure-controlled ventilation. The same measurements were performed twice.

RESULTS

Fifty ARDS patients were enrolled. MP was measured and calculated for a total of 300 measurements. The bias and limits of agreement were 0.38 from -1.31 to 2.0 J/min. The measured and calculated MP were similar in each ventilatory condition.

CONCLUSIONS

The mechanical power measured by a new automatic real time system implemented in a mechanical ventilator was repeatable and accurate compared with the computed one.

Immigration and Oral Health in Older Adults: An Integrative Approach

The aim of this study was to develop an integrative framework on aging, immigration, and oral health. The methodology was a critical review that used immigration as a social determinant framework through which to evaluate its impact on the oral health of older immigrants. We reviewed recent empirical evidence on factors related to oral health in older immigrants. In a systematic search across multiple databases, we identified 12 eligible studies in this review. Among the eligible studies, most were conducted among East Asian immigrants (8 articles), followed by non-Hispanic White/European origin (2 articles), Mexican origins (1 article), and Iran and other Middle East regions (1 article). The research revealed knowledge gaps in the evidence base, including the dynamic relationship between acculturation and oral health, the role of environmental factors on oral health for immigrants, psychosocial stressors and their relationship with oral health, and oral health literacy, norms, and attitude to dental care utilization and oral hygiene practices. The development of the integrative framework suggests the pathways/mechanisms through which immigration exerts influences on oral health in later life. This provides opportunities for researchers, practitioners, and policy makers to gain greater insights into the complex associations between immigration and oral health among older adults.

[Endemic situation of schistosomiasis in national surveillance sites of Hunan Province from 2015 to 2019]

OBJECTIVE

To analyze the changes in the endemic situation of schistosomiasis in national surveillance sites of Hunan Province, so as to provide scientific basis for the development of the schistosomiasis elimination programme in the province.

METHODS

According to the requirements of the National Guidelines for Schistosomiasis Surveillance in China (2014 version), a total of 41 national schistosomiasis surveillance sites were assigned in all disease-endemic counties (districts) across Hunan Province. During the period between 2015 and 2019, Schistosoma japonicum infections were monitored in local residents, mobile populations and livestock, and snail status was monitored. The morbidity due to schistosomiasis and snail status was compared between years.

RESULTS

The sero-prevalence of S. japonicum infections was 2.57% and 1.56% in local residents and mobile populations in national surveillance sites of Hunan Province from 2015 to 2019, respectively, and the sero-prevalence appeared a tendency towards a decline over years. A higher sero-prevalence rate of S. japonicum infections was seen in men than in women (P < 0.01). During the 5-year study period, the sero-prevalence rate of human S. japonicum infections appeared a tendency towards a decline in the marshland, embankment, inner embankment and hilly types of endemic areas over years. There were 44 and 19 egg -positives detected in local residents and 5 and 1 egg-positives in mobile populations in 2015 and 2016 respectively. A total of 9 346 domestic animals were monitored from 2015 to 2019, and 6 egg-positives were detected in 2015 and 2016 (all were bovine). A total of 0.155 billion m² settings were surveyed from 2015 to 2019, and the mean density of living snails appeared a tendency towards a decline over years, with a 45.79% reduction in 2019 as compared to 2015. However, no S. japonicum infections were identified in snails during the 5-year period. A total of 1 469 mixed snail samples were detected using loop-mediated isothermal amplification (LAMP), and 6 positive snail samples were identified in 2015 (one sample) and 2017 (5 samples).

CONCLUSIONS

The overall endemic situation of schistosomiasis appears a tendency towards a decline in Hunan Province, and the prevalence of S. japonicum infections is at a low level in humans and livestock; however, there is still a risk of schistosomiasis transmission. Improvements of health education, intensification of schistosomiasis examinations in mobile populations and reinforcement of the surveillance-response system is required to consolidate the achievements of schistosomiasis control in Hunan Province.

Acupuncture for recurrent urinary tract infection in women: a systematic review and meta-analysis

BACKGROUND

Increasing antibiotic resistance has motivated interest in non-antibiotic prophylaxis of recurrent urinary tract infections (rUTI).

OBJECTIVES

To conduct a systematic review of the current state of evidence of acupuncture for uncomplicated rUTI in women.

SEARCH STRATEGY

Nine databases (PubMed, Embase, CENTRAL, CINAHL, AMED, CBM, CNKI, CQVIP, Wanfang) were searched from inception to February 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating the effects of acupuncture and related therapies for prophylaxis or treatment of uncomplicated rUTI in women were included.

DATA COLLECTION AND ANALYSIS

Risk of bias was assessed, and the quality and strength of evidence evaluated using the GRADE framework. Results were reported as risk ratios (RR) for dichotomous outcomes or mean differences (MD) for continuous outcomes, with 95% confidence intervals (CI).

MAIN RESULTS

Five RCTs involving 341 participants were included. Methodological quality of studies and strength of the evidence were low to moderate. The chance of achieving a composite cure with acupuncture therapies was greater than that with antibiotics (three studies, 170 participants, RR 1.92, 95% CI 1.31-2.81, I²  = 38%). The risk of UTI recurrence was lower with acupuncture than with no treatment (two studies, 135 participants, RR 0.39, 95% CI 0.26-0.58, I²  = 0%) and sham acupuncture (one study, 53 participants, RR 0.45, 95% CI 0.22-0.92).

CONCLUSIONS

Acupuncture appeared to be beneficial for treatment and prophylaxis of rUTIs, noting the limitations of the current evidence. Given the growing challenge of antibiotic resistance, there is a need for high-quality RCTs of non-pharmacological interventions such as acupuncture.

TWEETABLE ABSTRACT

This review found that acupuncture may improve treatment and prevent recurrence of urinary tract infection in women.

Gefitinib promotes CXCR4-dependent epithelial to mesenchymal transition via TGF-β1 signaling pathway in lung cancer cells harboring EGFR mutation

PURPOSE

Epithelial to mesenchymal transition (EMT) plays an important role in acquired resistance to gefitinib in lung cancer. This study aimed to explore the underlying mechanism of gefitinib-induced EMT in lung adenocarcinoma cells harboring EGFR mutation.

METHODS

CXC chemokine receptor 4 (CXCR4) expression was determined through qRT-PCR, Western blot and flow cytometry assays in lung cancer cell line (PC9) bearing mutated EGFR. Functional role of CXCR4 was inhibited applying siRNAs as well as the specific antagonist AMD3100. The expression of EMT markers was determined, and the migration of PC9 cells was measured with transwell assay.

RESULTS

We found that gefitinib promoted the migratory capacity of PC9 cells in vitro, which correlated with EMT occurrence through upregulation of CXCR4. Blocking CXCR4 significantly suppressed gefitinib-induced enhancement of migration and EMT. Moreover, we determined that the upregulation of CXCR4 by gefitinib was dependent on TGF-β1/Smad2 signaling activity.

CONCLUSIONS

Our study suggested a potential mechanism by which gefitinib induced EMT in cells harboring EGFR mutation through a pathway involving TGF-β1 and CXCR4. Thus, the combination of CXCR4 antagonist and TGFβR inhibitors might provide an alternative strategy to overcome progression of lung cancer after gefitinib treatment.

Direct imaging of ultrafast lattice dynamics

Under rapid high-temperature, high-pressure loading, lattices exhibit complex elastic-inelastic responses. The dynamics of these responses are challenging to measure experimentally because of high sample density and extremely small relevant spatial and temporal scales. Here, we use an x-ray free-electron laser providing simultaneous in situ direct imaging and x-ray diffraction to spatially resolve lattice dynamics of silicon under high-strain rate conditions. We present the first imaging of a new intermediate elastic feature modulating compression along the axis of applied stress, and we identify the structure, compression, and density behind each observed wave. The ultrafast probe x-rays enabled time-resolved characterization of the intermediate elastic feature, which is leveraged to constrain kinetic inhibition of the phase transformation between 2 and 4 ns. These results not only address long-standing questions about the response of silicon under extreme environments but also demonstrate the potential for ultrafast direct measurements to illuminate new lattice dynamics.

[Outcomes of severe primary fetal hydrothorax treated by prenatal intervention]

Objective: To investigate the effect of intrauterine intervention on severe primary fetal hydrothorax. Methods: Twelve cases with severe fetal primary hydrothorax who underwent prenatal intervention from January 2014 to December 2017 in Guangdong Women and Children Hospital were retrospectively reviewed. Results: The median gestational age of prenatal diagnosis was 30.8 weeks (24.0-33.0 weeks) . All cases were excluded congenital chromosomal abnormalities by prenatal diagnosis, and had no complications of pregnancy during prenatal diagnosis and had hydrothorax. Three cases (3/12) were right hydrothorax, the other 9 cases (9/12) were bilateral. Thoracoamniotic shunting was performed in 7 cases (7/12) . Thoracentesis was performed in 5 cases (5/12) , and the hydrothorax reappeared soon after operation in 4 cases, shunt placement was performed again. The hydrothorax was dissolved in 2 cases, released in 6 cases.Tube falling off occurred in 1 case,treatment was abandoned in 1 case and intrauterine fetal death happened in 1 case, and 1 case wasn't rechecked by ultrasonic due to premature birth following thoracentesis. In 10 cases who had deliveries, 5 newborns (5/10) were premature, 6 newborns (6/10) underwent assisted mechanical ventilation, 8 newborns (8/10) underwent thoracic close drainage, all of them were discharged when hydrothorax resolved. Conclusions: Antenatal intervention may improve the chance of survival in severe primary fetal hydrothorax. Thoracoamniotic shunting is the first-choice for the primary severe fetal hydrothorax.

Hydro-nanofibrous mesh deep cell penetration: a strategy based on peeling of electrospun coaxial nanofibers

A two-step strategy for coaxial electrospinning and postelectrospinning is an effective method for fabricating superfine nanofibers composed of highly swellable hydrogels. Alginate and poly(ε-caprolactone) [PCL] were coelectrospun via fibrous meshes with a coaxial nozzle; alginate at the core was subsequently cross-linked in calcium chloride solution. The PCL sheath was removed from the meshes by repeated organic-phase washing. The peeling process was monitored by scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry, and the complete removal of the PCL outer layers was confirmed by the thinning of the fiber volume. The obtained alginate hydronanofiber showed extreme water-swellability and mass erosion depending on the degree of cross-linking. We also measured the nanoscale and macroscale mechanical properties of a single nanofiber and of the whole mesh by atomic force microscopy and rheometry. Quantitative analysis of nanomechanical properties indicated that the hydronanofiber with higher cross-linking density had higher stiffness and Derjaguin-Müller-Toporov modulus. Cells laid on the mesh and the vertical infiltration distance were visualized and quantified by confocal laser scanning microscopy. Cells on the mesh with higher cross-linking density infiltrated deeply to the bottom of the mesh. Thus, hydrogel-like nanofibrous meshes are versatile matrices allowing for deep infiltration of cells throughout the mesh via manipulation of the mechanical properties of the nanofiber.