Spatiotemporal Delivery Research Articles

Photoexcitation Dynamics of V-PYRRO/NO Investigated Using Femtosecond Time-Resolved Infrared Spectroscopy.

Diazeniumdiolates spontaneously release nitric oxide (NO) in aqueous solutions. Therefore, protected diazeniumdiolates have been developed for the controlled administration of NO to specific targets. Diazeniumdiolates with photoprotecting groups are useful for spatiotemporal NO delivery. To develop photoactivated NO donors, understanding the photodissociation dynamics of photoprotected diazeniumdiolates is essential. The dynamics of photoexcited V-PYRRO/NO (a well-studied liver-selective NO prodrug) was investigated to understand the photodissociation mechanism of protected diazeniumdiolates at the molecular level. Upon excitation at 305 nm, the N═N bond of V-PYRRO/NO was cleaved within 0.3 ps, producing N-nitrosopyrrolidine and CH2═CHON. CH2═CHON, the first oxynitrene directly observed in the solution in real-time, was formed in the singlet state and rearranged into CH2═CHNO with a time constant of 16 ± 5 ns. The calculated potential energy surfaces of the excited states confirmed the unusual breakage of the N═N bond. The findings can be utilized to develop more effective photoactivated diazeniumdiolates.

A Versatile Composite Hydrogel with Spatiotemporal Drug Delivery of Mesoporous ZnO and Recombinant Human Collagen for Diabetic Infected Wound Healing.

Diabetic wounds are increasingly common and challenging to treat due to high infection risks in a high-glucose environment. Effective treatment requires wound dressings that combat infections, while promoting angiogenesis and skin regeneration. This study presents a hydrogel-based drug delivery system made from cellulose designed to accelerate diabetic wound healing by eliminating bacterial infections. The hydrogel, formed by linking phenylboronic acid-grafted oxidized methylcellulose (POMC) with poly(vinyl alcohol) (PVA), exhibits self-healing and injectable properties. It is further enhanced by adding type I recombinant human collagen (rhCOL1) to stimulate cell growth and angiogenesis and mesoporous zinc oxide (mZnO) for antibacterial and anti-inflammatory effects. Upon application, the hydrogel degrades under pH/ROS stimuli, releasing mZnO and rhCOL1 in a controlled manner that matches the wound healing stages. In vivo tests show that the hydrogel effectively eliminates bacteria, reduces inflammation, and promotes rapid skin regeneration, making it a promising solution for treating diabetic wounds.

Micro-thin hydrogel coating integrated in 3D printing for spatiotemporal delivery of bioactive small molecules

Three-dimensional (3D) printing incorporated with controlled delivery is an effective tool for complex tissue regeneration. Here, we explored a new strategy for spatiotemporal delivery of bioactive cues by establishing a precise-controlled micro-thin coating of hydrogel carriers on 3D-printed scaffolds. We optimized the printing parameters for three hydrogel carriers, fibrin cross-linked with genipin, methacrylate hyaluronic acid, and multidomain peptides, resulting in homogenous micro-coating on desired locations in 3D printed polycaprolactone microfibers at each layer. Using the optimized multi-head printing technique, we successfully established spatial-controlled micro-thin coating of hydrogel layers containing profibrogenic small molecules (SMs), Oxotremorine M and PPBP maleate, and a chondrogenic cue, Kartogenin. The delivered SMs showed sustained releases up to 28 d and guided regional differentiation of mesenchymal stem cells, thus leading to fibrous and cartilaginous tissue matrix formation at designated scaffold regionsin vitroandin vivo. Our micro-coating of hydrogel carriers may serve as an efficient approach to achieve spatiotemporal delivery of various bioactive cues through 3D printed scaffolds for engineering complex tissues.

Therapeutic Controlled Release Strategies for Human Osteoarthritis.

Osteoarthritis is a progressive, irreversible debilitating whole joint disease that affects millions of people worldwide. Despite the availability of various options (non-pharmacological and pharmacological treatments and therapy, orthobiologics, and surgical interventions), none of them can definitively cure osteoarthritis in patients. Strategies based on the controlled release of therapeutic compounds via biocompatible materials may provide powerful tools to enhance the spatiotemporal delivery, expression, and activities of the candidate agents as a means to durably manage the pathological progression of osteoarthritis in the affected joints upon convenient intra-articular (injectable) delivery while reducing their clearance, dissemination, or side effects. The goal of this review is to describe the current knowledge and advancements of controlled release to treat osteoarthritis, from basic principles to applications in vivo using therapeutic recombinant molecules and drugs and more innovatively gene sequences, providing a degree of confidence to manage the disease in patients in a close future.

Cytotoxic potential of novel selenolato-bridged manganese(I)-based CORM and its molecular interaction with human serum albumin and DNA through spectroscopic and in silico docking studies

The prevalence of cancer is increasing steadily over the past few decades due to social and environmental factors. Several drugs and medications have also been reported, but with inevitable side effects. Herein comes the urgent need for the development of precision medicine, which increases the efficiency of the drug on the target tissue and minimizes systemic toxicity and non-specificity. One of the several approaches developed includes the formulation of smart or trigger-specific drugs for spatiotemporal delivery. In this view, an arena of carbon monoxide-releasing molecules (CORMs) that could be rendered trigger-specific using labile ligands has been developed. In the present investigation, one such novel, manganese based CORM (Mn-CORM) was synthesized and analysed for its selective cytotoxic potential. The Mn-CORM exerted a broad-spectrum cytotoxicity against cancer cells such as PAN C1 (pancreatic cancer), PC 3 (prostate cancer) and HT 29 (colon cancer). Present study further investigated the binding potential of Mn-CORM for human serum albumin (HSA), the major transporter of anticancer drugs and DNA using a multi-spectroscopic (UV-VIS absorption, quenching analysis, time resolved fluorescence spectroscopy, circular dichroism spectroscopy) and molecular docking techniques. The analysis of thermodynamic parameters ΔS0and ΔH0 showed that the binding of Mn-CORM to HSA was spontaneous and dominated by Van der Waals forces and hydrogen bonding. The binding potential of Mn-CORM for CT DNA was also investigated using spectroscopic studies, dye displacement assay, circular dichroism spectroscopy, thermal denaturation and DNA cleavage studies. Results demonstrated a good binding potential of Mn-CORM for CT DNA. The probable mode of binding of Mn-CORM and CT DNA was concluded to be a partial intercalation. All these experimental and computational results confirmed that the novel Mn-CORM used in the present study can be a promising anticancer agent.

Cell mediated reactions create TGF-β delivery limitations in engineered cartilage

During native cartilage development, endogenous TGF-β activity is tightly regulated by cell-mediated chemical reactions in the extracellular milieu (e.g., matrix and receptor binding), providing spatiotemporal control in a manner that is localized and short acting. These regulatory paradigms appear to be at odds with TGF-β delivery needs in tissue engineering (TE) where administered TGF-β is required to transport long distances or reside in tissues for extended durations. In this study, we perform a novel examination of the influence of cell-mediated reactions on the spatiotemporal distribution of administered TGF-β in cartilage TE applications. Reaction rates of TGF-β binding to cell-deposited ECM and TGF-β internalization by cell receptors are experimentally characterized in bovine chondrocyte-seeded tissue constructs. TGF-β binding to the construct ECM exhibits non-linear Brunauer–Emmett–Teller (BET) adsorption behavior, indicating that as many as seven TGF-β molecules can aggregate at a binding site. Cell-mediated TGF-β internalization rates exhibit a biphasic trend, following a Michaelis–Menten relation (Vmax = 2.4 molecules cell-1 s-1, Km = 1.7 ng mL-1) at low ligand doses (≤130 ng/mL), but exhibit an unanticipated non-saturating power trend at higher doses (≥130 ng/mL). Computational models are developed to illustrate the influence of these reactions on TGF-β spatiotemporal delivery profiles for conventional TGF-β administration platforms. For TGF-β delivery via supplementation in culture medium, these reactions give rise to pronounced steady state TGF-β spatial gradients; TGF-β concentration decays by ∼90 % at a depth of only 500 μm from the media-exposed surface. For TGF-β delivery via heparin-conjugated affinity scaffolds, cell mediated internalization reactions significantly reduce the TGF-β scaffold retention time (160–360-fold reduction) relative to acellular heparin scaffolds. This work establishes the significant limitations that cell-mediated chemical reactions engender for TGF-β delivery and highlights the need for novel delivery platforms that account for these reactions to achieve optimal TGF-β exposure profiles. Statement of significanceDuring native cartilage development, endogenous TGF-β activity is tightly regulated by cell-mediated chemical reactions in the extracellular milieu (e.g., matrix and receptor binding), providing spatiotemporal control in a manner that is localized and short acting. However, the effect of these reactions on the delivery of exogenous TGF-β to engineered cartilage tissues remains not well understood. In this study, we demonstrate that cell-mediated reactions significantly restrict the delivery of TGF-β to cells in engineered cartilage tissue constructs. For delivery via media supplementation, reactions significantly limit TGF-β penetration into constructs. For delivery via scaffold loading, reactions significantly limit TGF-β residence time in constructs. Overall, these results illustrate the impact of cell-mediated chemical reactions on TGF-β delivery profiles and support the importance of accounting for these reactions when designing TGF-β delivery platforms for promoting cartilage regeneration.

Spatiotemporal delivery of multiple components of rhubarb-astragalus formula for the sysnergistic treatment of renal fibrosis.

Rhubarb (Rheum palmatum L.) and astragalus (Radix astragali) find widespread used in clinical formulations for treating chronic kidney disease (CKD). Notably, the key active components, total rhubarb anthraquinone (TRA) and total astragalus saponin (TAS), exhibit superiority over rhubarb and astragalus in terms of their clear composition, stability, quality control, small dosage, and efficacy for disease treatment. Additionally, astragalus polysaccharides (APS) significantly contribute to the treatment of renal fibrosis by modulating the gut microbiota. However, due to differences in the biopharmaceutical properties of these components, achieving synergistic effects remains challenging. This study aims to develop combined pellets (CPs) and evaluate the potential effect on unilateral ureteral obstruction (UUO)-induced renal fibrosis. The CPs pellets were obtained by combining TRA/TAS-loaded SNEDDS pellets and APS-loaded pellets, prepared using the fluidized bed coating process. The prepared pellets underwent evaluation for morphology, bulk density, hardness, and flowing property. Moreover, the in vitro release of the payloads was evaluated with the CHP Type I method. Furthermore, the unilateral ureteral obstruction (UUO) model was utilized to investigate the potential effects of CPs pellets on renal fibrosis and their contribution to gut microbiota modulation. The ex-vivo study demonstrated that the developed CPs pellets not only improved the dissolution of TRA and TAS but also delivered TRA/TAS and APS spatiotemporally to the appropriate site along the gastrointestinal tract. In an animal model of renal fibrosis (UUO rats), oral administration of the CPs ameliorated kidney histological pathology, reduced collagen deposition, and decreased the levels of inflammatory cytokines. The CPs also restored the disturbed gut microbiota induced by UUO surgery and protected the intestinal barrier. The developed CPs pellets represent a promising strategy for efficiently delivering active components in traditional Chinese medicine formulas, offering an effective approach for treating CKD.

Comparison of two biologically effective dose calculation models applied to single fraction stereotactic radiosurgery

BackgroundRecent studies suggest strong correlations between Biologically Effective Doses (BED) and single fraction stereotactic radiosurgery treatment outcomes, as demonstrated for vestibular schwannomas (VS), arterio-venous malformations and pituitary adenomas. The BEDs calculated in these studies consider an uniform dose delivery where the spatio-temporal aspects of dose delivery were neglected. PurposeThe aim of the study is to quantify the discrepancies between the BED values calculated with a simplified model of uniform dose delivery against the more complex model that incorporates the temporo-spatial incrementation of dose delivery and the bi-exponential effect of the sub-lethal damage repair. MethodsA software tool that computes the BED distributions based on individual isocenter dose matrices extracted from the GammaPlan (Elekta) treatment planning was developed. Two cohorts 5 VS and 5 jugular foramen schwannoma cases of various tumor volumes and isocenter number were utilized to benchmark the method. Their BEDs covering 98% of tumor volumes were compared against those determined with the uniform delivery model. ResultsThe BEDs covering 98% of the tumor volumes as calculated with both models show an approximately linear dependency with the treatment time. For all studied cases, the uniform delivery model overestimates the BEDs calculated with the full spatio-temporal delivery model. This discrepancy seems to accentuate with the tumor volume and treatment complexity. ConclusionsDespite their resemblance, the BED distributions provide a plethora of BED measures more suitable to characterize clinical outcomes than the unique peripheral BED value calculated with the simplified model of uniform dose delivery.

Hydrogel and Microgel Collaboration for Spatiotemporal Delivery of Biofactors to Awaken Nucleus Pulposus-Derived Stem Cells for Endogenous Repair of Disc.

Depletion of nucleus pulposus-derived stem cells (NPSCs) is a major contributing factor to the attenuation of endogenous regenerative capacity in intervertebral disc degeneration (IVDD). Introducing a hydrogel drug delivery system is a potential strategy for counteracting endogenous cell depletion. The present study proposes a delivery platform for the spatiotemporal release of multiple drugs by combining sodium alginate hydrogels with gelatin microgels (SCGP hydrogels). The SCGP hydrogels facilitated the initial release of chondroitin sulfate (ChS) and the gradual release of an independently developed parathyroid hormone-related peptide (P2). The combined action of these two small molecule drugs "awakened" the reserve NPSCs, mitigated cell damage induced by H2O2, significantly enhanced their biological activity, and promoted their differentiation toward nucleus pulposus cells. The mechanical and viscoelastic properties of the hydrogel are enhanced by physical and chemical dual cross-linking to adapt to the loading environment of the degenerated disc. A rat IVDD model is used to validate that the SCGP hydrogel can significantly inhibit the progression of IVDD and stimulate the endogenous repair of IVDD. Therefore, the spatiotemporal differential drug delivery system of the SCGP hydrogel holds promise as a convenient and efficacious therapeutic strategy for minimally invasive IVDD treatment.

Spatiotemporal Delivery of Dual Nanobodies by Engineered Probiotics to Reverse Tumor Immunosuppression via Targeting Tumor-Derived Exosomes.

The anti-PD-L1 and its bispecific antibodies have exhibited durable antitumor immunity but still elicit immunosuppression mainly caused by tumor-derived exosomes (TDEs), leading to difficulty in clinical transformation. Herein, engineered Escherichia coli Nissle 1917 (EcN) coexpressing anti-PD-L1 and anti-CD9 nanobodies (EcN-Nb) are developed and decorated with zinc-based metal-organic frameworks (MOFs) loaded with indocyanine green (ICG), to generate EcN-Nb-ZIF-8CHO-ICG (ENZC) for spatiotemporal lysis of bacteria for immunotherapy. The tumor-homing hybrid system can specifically release nanobodies in response to near-infrared (NIR) radiation, thereby targeting TDEs and changing their biological distribution, remodeling tumor-associated macrophages to M1 states, activating more effective and cytotoxic T lymphocytes, and finally, leading to the inhibition of tumor proliferation and metastasis. Altogether, the microfluidic-enabled MOF-modified engineered probiotics target TDEs and activate the antitumor immune response in a spatiotemporally manipulated manner, offering promising TDE-targeted immune therapy.

In situ formed reactive oxygen species-responsive dipyridamole prodrug hydrogel: Spatiotemporal drug delivery for chemoimmunotherapy

In the realm of combined cancer immunotherapy, the strategic combination of therapeutics targeting both cancer cells and macrophages holds immense potential. However, the major challenges remain on how to achieve facile spatiotemporal delivery of these therapies, allowing ease of manipulation and ensuring differential drug release for enhanced synergistic therapeutic effects. In the present study, we introduced a tumor microenvironment (TME)-adapted hydrogel with the phenylboronic acid-modified dipyridamole prodrug (DIPP) as a crosslinker. This prodrug hydrogel scaffold, 3BP@DIPPGel, could be formed in situ by a simple mixture of DIPP and poly(vinyl alcohol) (PVA), and loaded with a high ratio of 3-bromopyruvic acid (3BP). The 3BP@DIPPGel enables spatiotemporal localized delivery of dipyridamole (DIP) and 3BP with distinct release kinetics that effectively reshape the immunosuppressive TME. Upon reactive oxygen species (ROS) stimulation, 3BP@DIPPGel preferentially released 3BP, inducing tumor-specific pyroptosis via the ROS/BAX/caspase-3/GSDME signaling pathway and decreasing the secretion of chemokines such as CCL8 to counteract macrophage recruitment. Subsequently, the crosslinked DIP is released, triggering the tumor-associated macrophages (TAMs) polarization towards the immunostimulatory M1 phenotype via the CCR2/JAK2/STAT3 cascade signaling pathway. This dual action from 3BP@DIPPGel leads to the restoration of tumor cell immunogenicity with high efficacy and activation of immune cells. Furthermore, the 3BP@DIPPGel-based chemoimmunotherapy upregulates the expression of sialic-acid-binding Ig-like lectin 10 and hence sensitizing tumors to anti-CD24 therapy in the tumor-bearing mice. Therefore, this strategy can have significant potential in the prevention of tumor metastases and recurrence. To the best of our understanding, this study represents a pioneering showcase of tumor pyroptosis, induced by glycolytic inhibitors, which can be effectively coordinated with DIP-mediated TAM polarization for immune activation, offering a new paradigm for differentially sustained drug delivery to foster cancer immunotherapy.

Dam regulation alters the spatio-temporal delivery of organic carbon along the Yellow River

Global river damming has significantly altered the riverine hydrodynamics and organic carbon (OC) delivery along the Land-to-Ocean Aquatic Continuum (LOAC). The Yellow River, one of the largest rivers in the world, has been under perturbation and fragmentation by dam construction. In this study, we quantified particulate OC (POC) and dissolved OC (DOC) fluxes, on daily-monthly-annual timescales, to explore the effects of dam-triggered perturbations on OC delivery in the Yellow River. We found that the “natural” seasonal delivery of OC upstream of the Xiaolangdi (XLD) reservoir had shifted to a heavily dam-regulated pattern downstream of the XLD reservoir. The dam-oriented Water-Sediment Regulation increased the periodic export of OC to the sea in June and July, as opposed to the natural flood season upstream of the XLD reservoir. The dam-modulated annual and inter-annual export of OC, from the Yellow River to the sea, is also teleconnected by El Niño/Southern Oscillation (ENSO) events. Historically known for its high POC flux, the Yellow River has seen a decline in POC/DOC ratios over the recent decades due to dam regulation. The dam-driven changes in organic carbon delivery along the Yellow River will continue to affect carbon cycling in its estuary and marginal seas.

Thermoresponsive lipids engineered magnetic nanoparticles for spatiotemporal delivery of hesperidin to inflammatory sites in animal model

Thermoresponsive nanoparticles are exploited as drug-delivery vehicles that release their payload upon increment in temperature. We prepared and characterized thermoresponsive lipid-anchored folic acid engineered magnetic nanoparticles (LP-HP-FANPs) that combine receptor-based targeting and thermoresponsive sustained release of hesperidin (HP) in response to endogenous inflammation site temperature. The progressive surface engineering of NPs was validated by FTIR analysis. Our LP-HP-FANPs had a particle size of 100.5 ± 1.76 nm and a zeta potential of 14.6 ± 2.65 mV. The HP encapsulation effectiveness of LP-HP-FANPs is around 91 ± 0.78%. AFM scans indicated that our modified nanoparticles were spherical. LP-HP-FANPs exhibit increased drug release (85.8% at pH 4.0, 50.9% at pH 7.0) at 40 °C. Animal studies showed no toxicity from nanoparticles. Compared to conventional drugs and HP, LP-HP-FANPs effectively decreased paw edema, cytokine levels, and total cell recruitment in thioglycollate-induced peritonitis (p < 0.05). LP-HP-FANPs substantially decreased cytokines compared to HP, HP-FA-NPs, and the standard medication (p < 0.05, p < 0.01, and p < 0.001). These findings imply that the synthesized HP-loaded formulation (LP-HP-FANPs) may be a potential anti-inflammatory formulation for clinical development.

Spatiotemporal delivery of microenvironment responsive hydrogel incorporated with stem cells-loaded porous microspheres for abdominal wall repair

Healing the wounds of abdominal wall defects characterised by severe complications represents a significant clinical challenge. Mesenchymal stem cells (MSC)-based therapies have emerged as a promising strategy for tissue regeneration. However, the low engraftment and survival rates limit their application owing to the complicated wound microenvironment and large wound areas in abdominal wall defects. Inspired by focal biointerfaces, the present research engineered a spatiotemporal delivery microenvironment-responsive therapeutic platform, termed MSC-GSM@HG, for abdominal wall repair. The constructed platform proved capable of dissolving HA-PBA/Gel-DA (HG) hydrogels in response to in vivo inflammatory responses and subsequently releasing MSC-laden gelatine and silk fibroin microspheres (GSMs). Meanwhile, the HG hydrogels can not only protect the MSCs from excessive reactive oxygen species but also exhibit haemostatic and anti-inflammatory properties. Strikingly, this microsphere-releasing hydrogel platform actively enhanced the repair of abdominal wall defects in vivo, by reducing inflammatory response, facilitating angiogenesis and promoting collagen deposition. Therefore, the microenvironment-responsive platform represents a promising strategy for MSC-based therapies for abdominal wall defects through spatiotemporal delivery mechanisms.

Unravelling the role of tumor microenvironment responsive nanobiomaterials in spatiotemporal controlled drug delivery for lung cancer therapy.

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Integrating Bioactive Graded Hydrogel with Radially Aligned Nanofibers to Dynamically Manipulate Wound Healing Process.

Skin wound healing is a complex process that requires appropriate treatment and management. Using a single scaffold to dynamically manipulate angiogenesis, cell migration and proliferation, and tissue reconstruction during skin wound healing is a great challenge. We developed a hybrid scaffold platform that integrates the spatiotemporal delivery of bioactive cues with topographical cues to dynamically manipulate the wound-healing process. The scaffold comprised gelatin methacryloyl hydrogels and electrospun poly(ε-caprolactone)/gelatin nanofibers. The hydrogels had graded cross-linking densities and were loaded with two different functional bioactive peptides. The nanofibers comprised a radially aligned nanofiber array layer and a layer of random fibers. During the early stages of wound healing, the KLTWQELYQLKYKGI peptide, which mimics vascular endothelial growth factor, was released from the inner layer of the hydrogel to accelerate angiogenesis. During the later stages of wound healing, the IKVAVS peptide, which promotes cell migration, synergized with the radially aligned nanofiber membrane to promote cell migration, while the nanofiber membrane also supported further cell proliferation. In an in vivo rat skin wound-healing model, the hybrid scaffold significantly accelerated wound healing and collagen deposition, and the ratio of type I to type III collagen at the wound site resembled that of normal skin. The prepared scaffold dynamically regulated the skin tissue regeneration process in stages to achieve rapid wound repair with clinical application potential, providing a strategy for skin wound repair.

Spatiotemporal delivery of BMP-2 and FGF-18 in 3D-bioprinted tri-phasic osteochondral scaffolds enhanced compartmentalized osteogenic and chondrogenic differentiation of mesenchymal stem cells isolated from rats with varied organizational morphologies

Replicating the heterogeneous structure and promoting compartmentalized osteogenesis/chondrogenesis are critical considerations in designing scaffolds for osteochondral tissue regeneration. However, desirable osteochondral regeneration cannot be achieved mainly due to the absence of effective delivery strategies for growth factors (GFs) and the insufficiency of desirable organizational morphologies for seed cells. Herein, we developed a tri-phasic osteochondral scaffold consisting of bone morphogenetic protein-2 (BMP-2)-loaded subchondral layer, fibroblast growth factor-18 (FGF-18)-loaded cartilage layer, and an interface layer that acted as a barrier to reduce the mutual interference of GFs, via cryogenic 3D bioprinting. BMP-2 could exert osteogenic effects for 14 days, and FGF-18 could exert chondrogenic effects for 21 days, demonstrating the time-controlled release function of BMP-2 and FGF-18. By further seeding discrete rat bone marrow mesenchymal stem cells (rBMSCs) and rBMSC microspheres, respectively, onto the subchondral layer and cartilage layer, the engineered cell-laden osteochondral tissue was constructed. The spatiotemporal release of BMP-2 and FGF-18 in the subchondral layer and cartilage layer promoted the osteogenic differentiation of discrete rBMSCs and chondrogenic differentiation of rBMSC microspheres in the subchondral layer and cartilage layer, respectively. In summary, by seeding rBMSCs with varied organizational morphologies in 3D-printed osteochondral scaffolds with a spatiotemporally controlled strategy, engineered osteochondral tissue with compartmentalized osteogenic/chondrogenic differentiation potent can be formed, displaying a facile and promising way to achieve desirable osteochondral tissue regeneration.

Cortisol, Stress, and Disease-Bidirectional Associations; Role for Corticosteroid-Binding Globulin?

Selye described stress as a unified neurohormonal mechanism maintaining homeostasis. Acute stress system activation is adaptive through neurocognitive, catecholaminergic, and immunomodulation mechanisms, followed by a reset via cortisol. Stress system components, the sympathoadrenomedullary system, hypothalamic-pituitary-adrenal axis, and limbic structures are implicated in many chronic diseases by establishing an altered homeostatic state, allostasis. Consequent "primary stress system disorders" were popularly accepted, with phenotypes based on conditions such as Cushing syndrome, pheochromocytoma, and adrenal insufficiency. Cardiometabolic and major depressive disorders are candidates for hypercortisolemic etiology, contrasting the "hypocortisolemic symptom triad" of stress sensitivity, chronic fatigue, and pain. However, acceptance of chronic stress etiology requires cause-and-effect associations, and practical utility such as therapeutics altering stress system function. Inherent predispositions to stress system perturbations may be relevant. Glucocorticoid receptor (GR) variants have been associated with metabolic/neuropsychological states. The SERPINA6 gene encoding corticosteroid-binding globulin (CBG), was the sole genetic factor in a single-nucleotide variation-genome-wide association study linkage study of morning plasma cortisol, a risk factor for cardiovascular disease, with alterations in tissue-specific GR-related gene expression. Studies showed genetically predicted high cortisol concentrations are associated with hypertension and anxiety, and low CBG concentrations/binding affinity, with the hypocortisolemic triad. Acquired CBG deficiency in septic shock results in 3-fold higher mortality when hydrocortisone administration produces equivocal results, consistent with CBG's role in spatiotemporal cortisol delivery. We propose some stress system disorders result from constitutional stress system variants rather than stressors themselves. Altered CBG:cortisol buffering may influence interstitial cortisol ultradian surges leading to pathological tissue effects, an example of stress system variants contributing to stress-related disorders.

Injectable Thermo-Responsive Peptide Hydrogels and Its Enzyme Triggered Dynamic Self-Assembly.

Endogenous stimuli-responsive injectable hydrogels hold significant promise for practical applications due to their spatio-temporal controllable drug delivery. Herein, we report a facile strategy to construct a series of in situ formation polypeptide hydrogels with thermal responsiveness and enzyme-triggered dynamic self-assembly. The thermo-responsive hydrogels are from the diblock random copolymer mPEG-b-P(Glu-co-Tyr). The L-glutamic acid (Glu) segments with different γ-alkyl groups, including methyl, ethyl, and n-butyl, offer specific secondary structure, facilitating the formation of hydrogel. The L-tyrosine (Tyr) residues not only provide hydrogen-bond interactions and thus adjust the sol-gel transition temperatures, but also endow polypeptide enzyme-responsive properties. The PTyr segments could be phosphorylated, and the phosphotyrosine copolymers were amphiphilies, which could readily self-assemble into spherical aggregates and transform into sheet-like structures upon dephosphorylation by alkaline phosphatase (ALP). P(MGlu-co-Tyr/P) and P(MGlu-co-Tyr) copolymers showed good compatibility with both MC3T3-E1 and Hela cells, with cell viability above 80% at concentrations up to 1000 μg/mL. The prepared injectable polypeptide hydrogel and its enzyme-triggered self-assemblies show particular potential for biomedical applications.

Cell-adhesive double network self-healing hydrogel capable of cell and drug encapsulation: New platform to construct biomimetic environment with bottom-up approach

This study presents the development and characterization of a novel double-network self-healing hydrogel based on N-carboxyethyl chitosan (CEC) and oxidized dextran (OD) with the incorporation of crosslinked collagen (CEC-OD/COL-GP) to enhance its biological and physicochemical properties. The hydrogel formed via dynamic imine bond formation exhibited efficient self-healing within 30 min, and a compressive modulus recovery of 92 % within 2 h. In addition to its self-healing ability, CEC-OD/COL-GP possesses unique physicochemical characteristics including transparency, injectability, and adhesiveness to various substrates and tissues. Cell encapsulation studies confirmed the biocompatibility and suitability of the hydrogel as a cell-culture scaffold, with the presence of a collagen network that enhances cell adhesion, spreading, long-term cell viability, and proliferation. Leveraging their unique properties, we engineered assemblies of self-healing hydrogel modules for controlled spatiotemporal drug delivery and constructed co-culture models that simulate angiogenesis in tumor microenvironments. Overall, the CEC-OD/COL-GP hydrogel is a versatile and promising material for biomedical applications, offering a bottom-up approach for constructing complex structures with self-healing capabilities, controlled drug release, and support for diverse cell types in 3D environments. This hydrogel platform has considerable potential for advancements in tissue engineering and therapeutic interventions.