Neural tissue engineering (TE) represents
a promising new avenue of therapy to support nerve recovery and regeneration.
To recreate the complex environment in which neurons develop and mature,
the ideal biomaterials for neural TE require a number of properties
and capabilities including the appropriate biochemical and physical
cues to adsorb and release specific growth factors. Here, we present
neural TE constructs based on electrospun serum albumin (SA) fibrous
scaffolds. We doped our SA scaffolds with an iron-containing porphyrin,
hemin, to confer conductivity, and then functionalized them with different
recombinant proteins and growth factors to ensure cell attachment
and proliferation. We demonstrated the potential for these constructs
combining topographical, biochemical, and electrical stimuli by testing
them with clinically relevant neural populations derived from human
induced pluripotent stem cells (hiPSCs). Our scaffolds could support
the attachment, proliferation, and neuronal differentiation of hiPSC-derived
neural stem cells (NSCs), and were also able to incorporate active
growth factors and release them over time, which modified the behavior
of cultured cells and substituted the need for growth factor supplementation
by media change. Electrical stimulation on the doped SA scaffold positively
influenced the maturation of neuronal populations, with neurons exhibiting
more branched neurites compared to controls. Through promotion of
cell proliferation, differentiation, and neurite branching of hiPSC-derived
NSCs, these conductive SA fibrous scaffolds are of broad application
in nerve regeneration strategies.
IntroductionRespiratory variation in arterial pulse pressure is a reliable predictor of fluid responsiveness in mechanically ventilated patients with circulatory failure. The main limitation of this method is that it requires an invasive arterial catheter. Both arterial and pulse oximetry plethysmographic waveforms depend on stroke volume. We conducted a prospective study to evaluate the relationship between respiratory variation in arterial pulse pressure and respiratory variation in pulse oximetry plethysmographic (POP) waveform amplitude.MethodThis prospective clinical investigation was conducted in 22 mechanically ventilated patients. Respiratory variation in arterial pulse pressure and respiratory variation in POP waveform amplitude were recorded simultaneously in a beat-to-beat evaluation, and were compared using a Spearman correlation test and a Bland–Altman analysis.ResultsThere was a strong correlation (r2 = 0.83; P < 0.001) and a good agreement (bias = 0.8 ± 3.5%) between respiratory variation in arterial pulse pressure and respiratory variation in POP waveform amplitude. A respiratory variation in POP waveform amplitude value above 15% allowed discrimination between patients with respiratory variation in arterial pulse pressure above 13% and those with variation of 13% or less (positive predictive value 100%).ConclusionRespiratory variation in arterial pulse pressure above 13% can be accurately predicted by a respiratory variation in POP waveform amplitude above 15%. This index has potential applications in patients who are not instrumented with an intra-arterial catheter.
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