Blood Plasma Derivatives for Tissue Engineering and Regenerative Medicine Therapies

Platelet-rich plasma (PRP) and its derivatives have been investigated and applied in regenerative medicine. The use of PRP as a supplement of cell culture media has consistently shown to potentiate stem cell proliferation, migration, and differentiation. In addition, the clinical utility of PRP is supported by evidence that PRP contains high concentrations of growth factors (GFs) and proteins which contribute to the regenerative process. PRP based therapies are cost effective and also benefit from the accessibility and safety of using the patient's own GFs. In the last years, a great development has been witnessed on PRP based biomaterials, with both structural and functional purposes. In this study we overview the most relevant PRP applications encompassing PRP based materials for tissue engineering and regenerative medicine. This review also summarizes the challenges in the fields of tissue engineering and regenerative medicine and provides a perspective on future directions.

Multifunctional laminarin microparticles for cell adhesion and expansion

Microfabrication technologies have been widely explored to produce microgels that can be assembled in functional constructs for tissue engineering and regenerative medicine applications. Here, we propose microfluidics coupled to a source of UV light to produce multifunctional methacrylated laminarin microparticles with narrow distribution of sizes using photopolymerization. The multifunctional microparticles were loaded with platelet lysates and further conjugated with an adhesive peptide. The adhesive peptides dictated cell adhesiveness to the laminarin microparticles, the incorporation of platelet lysates have resulted in improved cell expansion compared to clear microparticles. Overall, our findings demonstrate that multifunctional methacrylated laminarin microparticles provide an effective support for cell attachment and expansion. Moreover, expanded cells provide the link for microparticles aggregation resulting in robust 3D structures. This suggest the potential for using the methacrylated laminarin microplatforms capable to be assembled by the action of cells to rapidly produce large tissue engineered constructs.

Photopatterned antibodies for selective cell attachment

We present a phototriggerable system that allows for the spatiotemporal controlled attachment of selected cell types to a biomaterial using immobilized antibodies that specifically target individual cell phenotypes. o-Nitrobenzyl caged biotin was used to functionalize chitosan membranes and mediate site-specific coupling of streptavidin and biotinylated antibodies after light activation. The ability of this system to capture and immobilize specific cells on a surface was tested using endothelial-specific biotinylated antibodies and nonspecific ones as controls. Homogeneous patterned monolayers of human umbilical vein endothelial cells were obtained on CD31-functionalized surfaces. This is a simple and generic approach that is applicable to other ligands, materials, and cell types and shows the flexibility of caged ligands to trigger and control the interaction between cells and biomaterials.

Selective cell recruitment and spatially controlled cell attachment on instructive chitosan surfaces functionalized with antibodies

Bioactive constructs to guide cellular mobilization and function have been proposed as an approach for a new generation of biomaterials in functional tissue engineering. Adult mesenchymal stem cells have been widely used as a source for cell based therapeutic strategies, namely tissue engineering. This is a heterogeneous cell population containing many subpopulations with distinct regenerative capacity. Thus, one of the issues for the effective clinical use of stem cells in tissue engineering is the isolation of a highly purified, expandable specific subpopulation of stem cells. Antibody functionalized biomaterials could be promising candidates to isolate and recruit specific cell types. Here we propose a new concept of instructive biomaterials that are able to recruit and purify specific cell types from a mixed cell population. This biomimetic concept uses a target-specific chitosan substrate to capture specific adipose derived stem cells. Specific antibodies were covalently immobilized onto chitosan membranes using bis[sulfosuccinimidyl] suberate (BS3). Quartz crystal microbalance (QCM) was used to monitor antibody immobilization/adsorption onto the chitosan films. Specific antibodies covalently immobilized, kept their bioactivity and captured specific cell types from a mixed cell population. Microcontact printing allowed to covalently immobilize antibodies in patterns and simultaneously a spatial control in cell attachment.

Modeling of Cell-Mediated Self-Assembled Colloidal Scaffolds

A critical step in tissue engineering is the design and synthesis of 3D biocompatible matrices (scaffolds) to support and guide the proliferation of cells and tissue growth. The most existing techniques rely on the processing of scaffolds under controlled conditions and then implanting them in vivo, with questions related to biocompatibility and implantation that are still challenging. As an alternative, it was proposed to assemble the scaffolds in loco through the self-organization of colloidal particles mediated by cells. To overcome the difficulty to test experimentally all the relevant parameters, we propose the use of large-scale numerical simulation as a tool to reach useful predictive information and to interpret experimental results. Thus, in this study, we combine experiments, particle-based simulations, and mean-field calculations to show that, in general, the size of the self-assembled scaffold scales with the cell-to-particle ratio. However, we have found an optimal value of this ratio, for which the size of the scaffold is maximal when the cell-cell adhesion is suppressed. These results suggest that the size and structure of the self-assembled scaffolds may be designed by tuning the adhesion between cells in the colloidal suspension.

Elexacaftor/tezacaftor/ivacaftor-real-world clinical effectiveness and safety. A single-center Portuguese study

OBJECTIVE

To evaluate the effectiveness of treatment with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) and to characterize its safety profile in cystic fibrosis (CF) patients in a real-world clinical setting.

METHODS

This was a prospective observational study carried out in a CF referral center in Portugal involving adult CF patients who started treatment with ELX/TEZ/IVA. Clinical characteristics of the patients were collected, and effectiveness and safety data were evaluated.

RESULTS

Of the 56 patients followed in the center at the time of the study, 28 were eligible for ELX/TEZ/IVA treatment in accordance with the Portuguese National Authority for Medicines and Health Products at the time of the study. Of these, 24 met the follow-up time requirement to be included in the clinical effectiveness analysis. The mean follow-up time was 167.3 ± 96.4 days. Adverse events were generally mild and self-limited. Significant improvements in lung function, BMI, sweat chloride concentration, and number of pulmonary exacerbations were observed. No significant differences in outcomes between F508del homozygous and heterozygous patients were found. The effectiveness of this new CFTR modulator combination also applied to patients with advanced lung disease.

CONCLUSIONS

Treatment with ELX/TEZ/IVA showed effective improvement in real-world clinical practice, namely in lung function, BMI, sweat chloride concentration, and number of pulmonary exacerbations, with no safety concerns.

Influence of excessive daytime sleepiness on the treatment adherence of obstructive sleep apnea

OBJECTIVES

To compare positive airway pressure (PAP) adherence between patients with or without excessive daytime sleepiness (EDS) in mild, moderate and severe obstructive sleep apnea (OSA).

METHODS

Patients ≥18 years diagnosed with OSA in 2018 and 2019, without previous history of PAP usage and with adherence registration in the first medical consultation after treatment initiation, were included. EDS was defined as a score of ≥10 on the Epworth Scale. Patients were divided into two groups according to the adherence to PAP: "Adherent" if using the device for ≥4 h for ≥70% of the nights and "Nonadherent" otherwise. Simple and multiple logistic regression models for adherence were determined.

RESULTS

321 patients were included, most male (64.2%), with mean age 56.56 years. Most patients had severe OSA (n = 159; 49.5%), and median AHI was 29.3/h [16.8; 47.5]. Being older or having a severe OSA resulted in an increased adherence (OR = 1.020, CI95% = [1.002; 1.039] and OR = 2.299, CI95% = [1.273; 4.191], respectively). In patients without EDS a statistically significant difference was found in adherence between those with severe OSA and both mild and moderate OSA categories (OR = 0.285, p = 0.023 and OR = 0.387, p = 0.026, respectively), with patients with severe OSA being adherent. There was no statistical difference in adherence between patients with or without EDS (OR 1.083; p = 0.876), nor in the different degrees of severity in those with EDS.

CONCLUSION

In our study there were no differences in PAP therapy adherence between patients with or without excessive daytime sleepiness. Older age and higher OSA severity resulted in higher adherence rates.

Self-Assembly of Platelet Lysates Proteins into Microparticles by Unnatural Disulfide Bonds for Bottom-Up Tissue Engineering

There is a demand to design microparticles holding surface topography while presenting inherent bioactive cues for applications in the biomedical and biotechnological fields. Using the pool of proteins present in human-derived platelet lysates (PLs), the production of protein-based microparticles via a simple and cost-effective method is reported, exploring the prone redox behavior of cysteine (Cy-SH) amino acid residues. The forced formation of new intermolecular disulfide bonds results in the precipitation of the proteins as spherical, pompom-like microparticles with adjustable sizes (15-50 µm in diameter) and surface topography consisting of grooves and ridges. These PL microparticles exhibit extraordinary cytocompatibility, allowing cell-guided microaggregates to form, while also working as injectable systems for cell support. Early studies also suggest that the surface topography provided by these PL microparticles can support osteogenic behavior. Consequently, these PL microparticles may find use to create live tissues via bottom-up procedures or injectable tissue-defect fillers, particularly for bone regeneration, with the prospect of working under xeno-free conditions.

Supramolecular assembly of multi-purpose tissue engineering platforms from human extracellular matrix

Recapitulating the biophysical and biochemical complexity of the extracellular matrix (ECM) remains a major challenge in tissue engineering. Hydrogels derived from decellularized ECM provide a unique opportunity to replicate the architecture and bioactivity of native ECM, however, they exhibit limited long-term stability and mechanical integrity. In turn, materials assembled through supramolecular interactions have achieved considerable success in replicating the dynamic biophysical properties of the ECM. Here, we merge both methodologies by promoting the supramolecular assembly of decellularized human amniotic membrane (hAM), mediated by host-guest interactions between hAM proteins and acryloyl-β-cyclodextrin (AcβCD). Photopolymerization of the cyclodextrins results in the formation of soft hydrogels that exhibit tunable stress relaxation and strain-stiffening. Disaggregation of bulk hydrogels yields an injectable granular material that self-reconstitutes into shape-adaptable bulk hydrogels, supporting cell delivery and promoting neovascularization. Additionally, cells encapsulated within bulk hydrogels sense and respond to the biophysical properties of the surrounding matrix, as early cell spreading is favored in hydrogels that exhibit greater susceptibility to applied stress, evidencing proper cell-matrix interplay. Thus, this system is shown to be a promising substitute for native ECM in tissue repair and modelling.