Biology subjects

Rossi, R. M.

Publications and source records attributed to Rossi, R. M..

9 recordsLinked to original sources

bioRxiv2026

A dermal-epidermal junction-inclusive skin model enabled by controllable hydrogel swelling

Tissue engineered skin models are important tools for the in vitro study of physiological and pathophysiological processes as well as the evaluation of therapeutic strategies and the efficacy of pharmaceutical and cosmetic compounds. Replicating the functional anatomy of cutaneous tissue is a crucial aspect in ensuring that observations made using these models are translatable to the actual situation in native skin. However, most contemporary full-thickness skin models neglect the reconstruction of the undulated microtopography of the dermal-epidermal junction (DEJ), which not only contributes to the biological functionality of the skin (e.g. stem cell niches), but also affects tissue mechanics and drug diffusion. Herein, we fabricated bilayer skin models with DEJ-like microtopographies introduced by interfacial wrinkling between a hydrogel and a nanofibrous membrane through a controllable swelling-deswelling approach. The interfacial wrinkles contributed to the structural integrity of the bilayer models. Their formation could be induced in the presence of living cells through mechanical stress-driven buckling instabilities, thus differentiating the process from commonly used pre-patterning techniques. Bilayer models supported the co-culture of human dermal fibroblasts and human epidermal keratinocytes, and the formation of stratified epithelia. Our findings provide a potential alternative method to introduce DEJ-like anatomical features into full-thickness skin tissue models.

bioengineering↗

bioRxiv2025

Towards light responsive hydrogel-based valves for flow regulation

Smart hydrogels are promising materials for soft actuators in biomedical applications thanks to their varied responses to external stimuli. Light is a particularly attractive trigger for contactless stimulation of hydrogels that can induce reversible morphological changes without damaging the fragile gels. To meet the varied needs of applications in microfluidics, soft robotics, biomedicine, and other fields, there is significant demand for novel valve designs that are highly tunable, miniaturizable, and respond quickly to stimuli while maintaining their function over many activation cycles. Additionally, it is crucial to develop a more quantitative understanding of the mechanics of valve operation in response to different stimuli, especially when active hydrogels are combined with other materials in multi-component devices. Here, stimuli-responsive valves are fabricated using active hydrogels deformed upon temperature changes and exposure to near-infrared radiation. Gold nanorods (AuNRs) acting as photothermal transducers are embedded inside N-isopropylacrylamide (NIPAM), allowing local morphological changes in response to light with high spatiotemporal control. These changes are described precisely as a function of the valves confinement, aspect ratio, and the parameters of the stimulus using quantitative image analysis, providing novel mechanistic insights. Changing the aspect ratio of the valves and the degree of confinement of the hydrogel causes valves to either open or close during heating and can be used to control the magnitude of their response to different stimuli. These varied morphological changes are due to local, inhomogeneous deformations of the gel. The use of light as a trigger enables local confinement of the valve, reversible opening and closing, and fast response times on the order of seconds. The valves are shown to withstand hydrostatic pressures of up to 18 kPa, providing high potential for biomedical applications where precise pressure control and quick switching between open and closed states is critical. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/686031v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@239b78org.highwire.dtl.DTLVardef@1b40b5corg.highwire.dtl.DTLVardef@155c6eaorg.highwire.dtl.DTLVardef@763dbf_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2022

Intranasal virus-particle mimicking vaccine enhances SARS-CoV-2 clearance in the Syrian hamster model

Multiple vaccines have been developed and licensed for SARS-CoV-2. While these vaccines reduce disease severity, they do not prevent infection, and SARS-CoV-2 continues to spread and evolve. To prevent infection and limit transmission, vaccines must be developed that induce immunity in the respiratory tract. Therefore, we performed proof-of-principle vaccination studies with an intranasal nanoparticle vaccine against SARS-CoV-2. The vaccine candidate consisted of the self-assembling 60-subunit I3-01 protein scaffold covalently decorated with the SARS-CoV-2 receptor binding domain (RBD) using the SpyCatcher-SpyTag system. We verified the intended antigen display features by reconstructing the I3-01 scaffold to 3.4A using cryo-EM, and then demonstrated that the scaffold was highly saturated when grafted with RBD. Using this RBD-grafted SpyCage scaffold (RBD+SpyCage), we performed two unadjuvanted intranasal vaccination studies in the "gold-standard" preclinical Syrian hamster model. Hamsters received two vaccinations 28 days apart, and were then challenged 28 days post-boost with SARS-CoV-2. The initial study focused on assessing the immunogenicity of RBD+SpyCage, which indicated that vaccination of hamsters induced a non-neutralizing antibody response that enhanced viral clearance but did not prevent infection. In an expanded study, we demonstrated that covalent bonding of RBD to the scaffold was required to induce an antibody response. Consistent with the initial study, animals vaccinated with RBD+SpyCage more rapidly cleared SARS-CoV-2 from both the upper and lower respiratory tract. These findings demonstrate the intranasal SpyCage vaccine platform can induce protection against SARS-CoV-2 and, with additional modifications to improve immunogenicity, is a versatile platform for the development of intranasal vaccines targeting respiratory pathogens. IMPORTANCEDespite the availability of efficacious COVID vaccines that reduce disease severity, SARS-CoV-2 continues to spread. To limit SARS-CoV-2 transmission, the next generation of vaccines must induce immunity in the mucosa of the upper respiratory tract. Therefore, we performed proof-of-principle, unadjuvanted intranasal vaccination studies with a recombinant protein nanoparticle scaffold, SpyCage, decorated with the receptor-binding domain (RBD) of the S protein (SpyCage+RBD). We show that SpyCage+RBD was immunogenic and enhanced SARS-CoV-2 clearance from the nose and lungs of Syrian hamsters. Moreover, covalent grafting of the RBD to the scaffold was required to induce an immune response when given via the intranasal route. These proof-of-concept findings indicate that with further enhancements to immunogenicity (e.g., adjuvant incorporation, antigen optimization), the SpyCage scaffold has potential as a versatile, intranasal vaccine platform for respiratory pathogens.

immunology↗

bioRxiv2022

Changes in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume and immunoglobulins content

The objective of this observational study was to compare the metabolic status of dairy cows during the last 6 wk of gestation based on colostrum volume and Ig content. For this, healthy Holstein cows were randomly selected from 3 commercial herds in Michigan. In each farm, four cohorts of 21 cows (one per season), stratified by parity, were enrolled (n=228). Cows were blood sampled weekly during the last 6 wk of gestation, and biomarkers related to nutrient utilization, oxidant status, and inflammation were quantified in serum. Cows were milked within 6 h of calving and the volume of colostrum produced was recorded and an aliquot collected. Concentration of IgG, IgA, and IgM were measured by radial immunodiffusion. Cows were grouped into high colostrum producer (HCP) or low (LCP), high IgG (HIG) or low (LIG), high IgA (HIA) or low (LIA), and high IgM (HIM) or low (LIM). For volume category, we arbitrarily defined 6 L of colostrum (4 L for first and 2 L for second feeding of calves) as the cut-off point, whereas for IgG we used the industry standard of [≥] 50g/L. To create groups of low and high IgM or IgA, we used the median of these Ig as the cutoff point. Colostrum volume was lowest in winter, but no differences were observed among parity groups. Conversely, colostrum IgG concentration was highest in fall and winter, but colostrum IgM was lowest at these seasons. However, colostrum Ig content only showed a negative weak correlation with volume (Spearman rho < -0.28). Compared to LCP, HCP cows had higher concentrations of antioxidant potential, BHB and lower cholesterol and oxidant status index. HIG cows showed higher concentrations of glucose compared to LIG. HIA cows had higher concentrations of cholesterol, reactive oxygen and nitrogen species, oxidant status index, and total protein, while BHB, and glucose were lower compared with LIA. Biomarkers of metabolic stress were not significantly different between HIM and LIM. Nevertheless, the differences observed did not result in differences in inflammatory status between animals in any of the colostrum variable categories analyzed, suggesting that physiological homeostasis was not disrupted during late gestation in association with the colostrum variables studied. Overall, the great variability observed in colostrum variables suggests that colostrogenesis is a complex and multifactorial process. However, our results suggest that greater availability of antioxidants during late gestation could support the production of higher volumes of colostrum, which needs to be explored in future trials. INTERPRETIVE SUMMARYChanges in biomarkers of metabolic stress during late gestation of dairy cows associated with colostrum volume and immunoglobulins content. By Rossi et al., page XXXX. We investigated associations between metabolic stress during the last 6 wk of gestation and the volume and immunoglobulin content of the colostrum produced. We observed that cows producing more than 6 L of colostrum exhibited increased metabolic activity during late gestation. Also, a greater blood antioxidant activity throughout late gestation was observed in cows with higher yields of colostrum, suggesting that greater availability of antioxidants might support the production of higher volumes of colostrum. Therefore, further studies should evaluate whether supplementation with additional antioxidants supplement during late gestation can improve colostrum yield.

immunology↗

bioRxiv2021

Predicting transdermal fentanyl delivery using physics-based simulations for tailored therapy

Transdermal fentanyl patches are an effective alternative to the sustained-release of oral morphine for chronic pain treatment. Due to the narrow therapeutic range of fentanyl, the fentanyl concentration in the blood needs to be controlled carefully. Only then, effective pain relief can be reached while avoiding adverse effects such as respiratory depression. In this study, a physics-based digital twin of the patient was developed by implementing mechanistic models for transdermal drug uptake and the patients pharmacokinetic and pharmacodynamics response. A digital twin is a virtual representation of the patient and the transdermal drug delivery system, which is linked to the real-world patient by patient feedback, sensor data of specific biomarkers, or customizing the twin to a particular patient characteristic, for example, based on the age. This digital twin can predict the transdermal drug delivery processes in-silico. Our twin is used first to predict conventional therapys effect for using fentanyl patches on a virtual patient at different ages. The results show that by aging, the maximum transdermal fentanyl flux and maximum concentration of fentanyl in the blood decrease by 11.4% and 7.0%, respectively. Nonetheless, by aging, the pain relief increases by 45.2% despite the lower concentration of fentanyl in the blood for older patients. As a next step, the digital twin was used to propose a tailored therapy, based on the patients age, to deliver fentanyl based on the patients needs to alleviate pain. This predesigned therapy consisted of customizing the duration of applying and changing the commercialized fentanyl patches based on the calculated pain intensity. According to this therapy, a patient of 20 years old needs to change the patch 2.1 times more frequently compared to conventional therapy, which led to 30% more pain relief and 315% more time without pain. In addition, the digital twin was updated by the patients pain intensity feedback. Such therapy led to an increase in the patients breathing rate while having effective pain relief, therefore providing a safer and more comfortable treatment for the patient. We quantified the added value of a patients physics-based digital twin and sketched the future roadmap for implementing such twin-assisted treatment into the clinics. NomenclatureO_ST_ABSSymbolsC_ST_ABSci The concentration of fentanyl in layer i (in the drug uptake model) [ng ml-1] cp The concentration of fentanyl in the central compartment [ng ml-1] cr The concentration of fentanyl in the rapid equilibrated compartment [ng ml-1] cs The concentration of fentanyl in the slow equilibrated compartment [ng ml-1] cg The concentration of fentanyl in the gastrointestinal compartment [ng ml-1] cl The concentration of fentanyl in the hepatic compartment [ng ml-1] ce The concentration of fentanyl in the effect compartment [ng ml-1] Di Diffusion coefficient of fentanyl in layer i (in the mechanistic model) [m2 s-1] D0 Base diffusion coefficient of fentanyl [m2 s-1] DT Diffusion coefficient of fentanyl at temperature T [m2 s-1] D306 Diffusion coefficient of fentanyl at 306[K] [m2 s-1] dpt The thickness of the transdermal patch [{micro}m] dsc The thickness of the stratum corneum [{micro}m] dvep The thickness of the viable epidermis [{micro}m] dEdm The thickness of the equivalent dermis [{micro}m] Ei The intensity of effect i [Formula]The baseline of effect i [Formula]The maximum effect i EC50,i The concentration related to half-maximum effect i [ng ml-1] fu The fraction of unbound fentanyl in plasma ji Fentanyl flux in layer i (in the mechanistic model) Ki/j The partition coefficient of fentanyl between layer i to j (in the mechanistic model) Ki The drug capacity in layer i (in the mechanistic model) kcs Inter-compartmental first-order equilibrium rate constant (central to slow equilibrated) [min-1] kcr Inter-compartmental first-order equilibrium rate constant (central to rapid equilibrated) [min-1] kcg Inter-compartmental first-order equilibrium rate constant (central to gastrointestinal) [min-1] kch Inter-compartmental first-order equilibrium rate constant (central to hepatic) [min-1] ksc Inter-compartmental first-order equilibrium rate constant (slow equilibrated to central) [min-1] krc Inter-compartmental first-order equilibrium rate constant (rapid equilibrated to central) [min-1] khc Inter-compartmental first-order equilibrium rate constant (hepatic to central) [min-1] kgh Inter-compartmental first-order equilibrium rate constant (gastrointestinal to hepatic) [min-1] kmet Metabolization rate constant [min-1] kre Renal clearance rate constant [min-1] ke Inter-compartmental first-order equilibrium rate constant (for effect compartment) [min-1] SI Sensitivity index t Time [h] tD Time lag [h] [Formula]Dependent variable related to xi for sensitivity analysis Vc The apparent volume of the central compartment [L] Vs The apparent volume of the slow equilibrated compartment [L] Vr The apparent volume of the rapid equilibrated compartment [L] Vg The apparent volume of the gastrointestinal compartment [L] Vh The apparent volume of the hepatic compartment [L] xi The independent variable which sensitivity analysis is done based on it {gamma}Hill coefficient {psi}i Drug potential in domain i [ng ml-1]

pharmacology and toxicology↗

bioRxiv2020

Inverse mechanistic modeling of transdermal drug delivery for fast identification of optimal model parameters

Transdermal drug delivery systems are a key technology to administer drugs with a high first-pass effect in a non-invasive and controlled way. Physics-based modeling and simulation are on their way to become a cornerstone in the engineering of these healthcare devices since it provides a unique complementarity to experimental data and insights. Simulations enable to virtually probe the drug transport inside the skin at each point in time and space. However, the tedious experimental or numerical determination of material properties currently forms a bottleneck in the modeling workflow. We show that multiparameter inverse modeling to determine the drug diffusion and partition coefficients is a fast and reliable alternative. We demonstrate this strategy for transdermal delivery of fentanyl. We found that inverse modeling reduced the normalized root mean square deviation of the measured drug uptake flux from 26 to 9%, when compared to the experimental measurement of all skin properties. We found that this improved agreement with experiments was only possible if the diffusion in the reservoir holding the drug was smaller than the experimentally-measured diffusion coefficients suggested. For indirect inverse modeling, which systematically explores the entire parametric space, 30 000 simulations were required. By relying on direct inverse modeling, we reduced the number of simulations to be performed to only 300, so a factor 100 difference. The modeling approachs added value is that it can be calibrated once in-silico for all model parameters simultaneously by solely relying on a single measurement of the drug uptake flux evolution over time. We showed that this calibrated model could accurately be used to simulate transdermal patches with other drug doses. We showed that inverse modeling is a fast way to build up an accurate mechanistic model for drug delivery. This strategy opens the door to clinically-ready therapy that is tailored to patients.

pharmacology and toxicology↗

bioRxiv2020

Predicting transdermal fentanyl delivery using mechanistic simulations for tailored therapy

Transdermal drug delivery is a key technology for administering drugs. However, most devices are "one-size-fits-all", even though drug diffusion through the skin varies significantly from person-to-person. For next-generation devices, personalization for optimal drug release would benefit from an augmented insight into the drug release and percutaneous uptake kinetics. Our objective was to quantify the changes in transdermal fentanyl uptake with regards to the patients age and the anatomical location where the patch was placed. We also explored to which extent the drug flux from the patch could be altered by miniaturizing the contact surface area of the patch reservoir with the skin. To this end, we used validated mechanistic modeling of fentanyl diffusion, storage, and partitioning in the epidermis to quantify drug release from the patch and the uptake within the skin. A superior spatiotemporal resolution compared to experimental methods enabled in-silico identification of peak concentrations and fluxes, and the amount of stored drug and bioavailability. The patients drug uptake showed a 36% difference between different anatomical locations after 72 h, but there was a strong interpatient variability. With aging, the drug uptake from the transdermal patch became slower and less potent. A 70-year-old patient received 26% less drug over the 72-h application period, compared to an 18-year-old patient. Additionally, a novel concept of using micron-sized drug reservoirs was explored in silico. These reservoirs induced a much higher local flux ({micro}g cm-2 h-1) than conventional patches. Up to a 200-fold increase in the drug flux was obtained from these small reservoirs. This effect was mainly caused by transverse diffusion in the stratum corneum, which is not relevant for much larger conventional patches. These micron-sized drug reservoirs open new ways to individualize reservoir design and thus transdermal therapy. Such computer-aided engineering tools also have great potential for in-silico design and precise control of drug delivery systems. Here, the validated mechanistic models can serve as a key building block for developing digital twins for transdermal drug delivery systems.

bioengineering↗

bioRxiv2020

Relationship between Anti-Spike Protein Antibody Titers and SARS-CoV-2 In Vitro Virus Neutralization in Convalescent Plasma

Newly emerged pathogens such as SARS-CoV-2 highlight the urgent need for assays that detect levels of neutralizing antibodies that may be protective. We studied the relationship between anti-spike ectodomain (ECD) and anti-receptor binding domain (RBD) IgG titers, and SARS-CoV-2 virus neutralization (VN) titers generated by two different in vitro assays using convalescent plasma samples obtained from 68 COVID-19 patients, including 13 who donated plasma multiple times. Only 23% (16/68) of donors had been hospitalized. We also studied 16 samples from subjects found to have anti-spike protein IgG during surveillance screening of asymptomatic individuals. We report a strong positive correlation between both plasma anti-RBD and anti-ECD IgG titers, and in vitro VN titer. Anti-RBD plasma IgG correlated slightly better than anti-ECD IgG titer with VN titer. The probability of a VN titer [≥]160 was 80% or greater with anti-RBD or anti-ECD titers of [≥]1:1350. Thirty-seven percent (25/68) of convalescent plasma donors lacked VN titers [≥]160, the FDA-recommended level for convalescent plasma used for COVID-19 treatment. Dyspnea, hospitalization, and disease severity were significantly associated with higher VN titer. Frequent donation of convalescent plasma did not significantly decrease either VN or IgG titers. Analysis of 2,814 asymptomatic adults found 27 individuals with anti-RBD or anti-ECD IgG titers of [≥]1:1350, and evidence of VN [≥]1:160. Taken together, we conclude that anti-RBD or anti-ECD IgG titers can serve as a surrogate for VN titers to identify suitable plasma donors. Plasma anti-RBD or anti-ECD titer of [≥]1:1350 may provide critical information about protection against COVID-19 disease.

immunology↗

bioRxiv2018

Variants in the fetal genome near pro-inflammatory cytokine genes on 2q13 are associated with gestational duration

The duration of pregnancy is influenced by fetal and maternal genetic and non-genetic factors. We conducted a fetal genome-wide association meta-analysis of gestational duration, and early preterm, preterm, and postterm birth in 84,689 infants. One locus on chromosome 2q13 was associated with gestational duration; the association was replicated in 9,291 additional infants (combined P = 3.96 x 10-14). Analysis of 15,536 mother-child pairs showed that the association was driven by fetal rather than maternal genotype. Functional experiments showed that the lead SNP, rs7594852, alters the binding of the HIC1 transcriptional repressor. Genes at the locus include several interleukin 1 family members with roles in pro-inflammatory pathways that are central to the process of parturition. Further understanding of the underlying mechanisms will be of great public health importance, since giving birth either before or after the window of term gestation is associated with increased morbidity and mortality.

genetics↗