Nuria Vilaboa

We have developed a remotely near-infrared (NIR)-activated, implantable fibrin hydrogel for the controlled induction of transgene expression, designed to decouple the therapeutic efficacy of rapamycin from its systemic toxicity. Rapamycin, a drug widely used in clinical practice as an immunosuppressant and antiproliferative agent, is a potent transcriptional inducer that enables tightly regulated temporal transgene expression through chemically induced dimerization. However, its utility as a dimerizer is hindered by the unintended systemic immunosuppression and off-target effects inherent to its conventional administration. To address this, we developed poly(lactic-co-glycolic acid) (PLGA) nanoparticles to encapsulate rapamycin, aiming to facilitate localized delivery and enhance drug stability. Engineered cells harboring a dual heat- and dimerizer-responsive gene switch exhibited robust reporter transgene expression following nanoparticle treatment and thermal activation. Nanoencapsulation preserved rapamycin activity against thermal and hydrolytic degradation, enabling superior, long-term dimerizer function compared to the free drug. To create a remotely actuated platform, we developed photothermal hydrogels by incorporating hollow gold nanoparticles and rapamycin-loaded PLGA nanoparticles within a fibrin matrix hosting the reporter cells. In mice, NIR irradiation of subcutaneously implanted constructs achieved transgene induction levels comparable to systemic administration of rapamycin. Notably, nanoparticle-mediated delivery resulted in negligible circulating rapamycin concentrations. Furthermore, localized rapamycin release initially promoted a pro-healing M2 macrophage phenotype, followed by a late-stage transition toward an M1-dominant profile that likely facilitated the clearance of scaffold degradation products. In hydrogels incorporating cells harboring a gene switch to control human VEGF165 production, NIR irradiation triggered a robust angiogenic cascade characterized by transient erythema followed by an increase in CD31⁺ microvascular density. Collectively, these data demonstrate the potential of this light-triggered and rapamycin-dependent platform as a customizable and safe tool for achieving the control required to advance the next-generation of site-specific, transgenic protein therapies.

The development of bioabsorbable biomaterials with surface properties that promote tissue integration while preventing bacterial colonization remains a major challenge in biomedical engineering. In this study, polylactic acid (PLA) films with tailored surface microtopographies were fabricated through a simple and scalable solvent casting approach by incorporating surfactants with different chemical natures: sodium dodecylsulphate (SDS), hexadecyltrimethylammonium bromide (CTAB) and polysorbate 20 (Tween-20, T20). Magnesium particles were also incorporated as a biodegradable antibacterial additive and to improve the mechanical behaviour of PLA. Surface morphology and topography were analyzed by atomic force microscopy and optical profilometry, while wettability and surface free energy were assessed by contact angle measurements. The biological performance of the films was evaluated using Staphylococcus epidermidis adhesion and biofilm formation assays, together with cell viability studies employing HaCaT human keratinocytes.Distinct and reproducible surface microstructures were generated depending on the surfactant employed, including conical protrusions, isotropically distributed microcavities, and spiral-like patterns. Surfactant incorporation reduced bacterial adhesion relative to pristine PLA, an effect further enhanced by magnesium addition, which led to the total inhibition of viable biofilms on CTAB- and SDS-containing samples. In contrast to samples incorporating CTAB or SDS, T20-modified PLA supported keratinocyte adhesion and long-term viability, even in the presence of magnesium. These results establish surfactant-induced microstructuring as a powerful and unexplored strategy for modulating the biological response of PLA, opening new avenues for the design of bioabsorbable biomedical devices for wound healing.

Vaccination with transiently activated replication-competent controlled herpesviruses (RCCVs) expressing influenza A virus hemagglutinins broadly protects mice against lethal influenza virus challenges. The non-replicating RCCVs can be activated to transiently replicate with high efficiency. Activation involves a brief heat treatment to the epidermal administration site in the presence of a drug. The drug co-control is intended as a block to inadvertent reactivation in the nervous system and, secondarily, viremia under adverse conditions. While the broad protective effects observed raise an expectation that RCCVs may be developed as universal flu vaccines, the need for administering a co-activating drug may dampen enthusiasm for such a development. To replace the drug co-control, we isolated keratin gene promoters that were active in skin cells but inactive in nerve cells and other cells in vitro. In a mouse model of lethal central nervous system (CNS) infection, the administration of a recombinant that had the promoter of the infected cell protein 8 (ICP8) gene of a wild-type herpes simplex virus 1 (HSV-1) strain replaced by a keratin promoter did not result in any clinical signs, even at doses of 500 times wild-type virus LD₅₀. Replication of the recombinant was undetectable in brain homogenates. Second-generation RCCVs expressing a subtype H1 hemagglutinin (HA) were generated in which the infected cell protein 4 (ICP4) genes were controlled by a heat switch and the ICP8 gene by the keratin promoter. In mice, these RCCVs replicated efficiently and in a heat-controlled fashion in the epidermal administration site. Immunization with the activated RCCVs induced robust neutralizing antibody responses against influenza viruses and protected against heterologous and cross-group influenza virus challenges.

A universal vaccine that generally prevents influenza virus infection and/or illness remains elusive. We have been exploring a novel approach to vaccination involving replication-competent controlled herpesviruses (RCCVs) that can be deliberately activated to replicate efficiently but only transiently in an administration site in the skin of a subject. The RCCVs are derived from a virulent wild-type herpesvirus strain that has been engineered to contain a heat shock promoter-based gene switch that controls the expression of, typically, two replication-essential viral genes. Additional safety against inadvertent replication is provided by an appropriate secondary mechanism. Our first-generation RCCVs can be activated at the administration site by a mild local heat treatment in the presence of an antiprogestin. Here, we report that epidermal vaccination with such RCCVs expressing a hemagglutinin or neuraminidase of an H1N1 influenza virus strain protected mice against lethal challenges by H1N1 virus strains representing 75 years of evolution. Moreover, immunization with an RCCV expressing a subtype H1 hemagglutinin afforded full protection against a lethal challenge by an H3N2 influenza strain, and an RCCV expressing a subtype H3 hemagglutinin protected against a lethal challenge by an H1N1 strain. Vaccinated animals continued to gain weight normally after the challenge. Protective effects were even observed in a lethal influenza B virus challenge. The RCCV-based vaccines induced robust titers of in-group, cross-group and even cross-type neutralizing antibodies. Passive immunization suggested that observed vaccine effects were at least partially antibody-mediated. In summary, RCCVs expressing a hemagglutinin induce robust and very broad cross-protective immunity against influenza.

BONE TISSUE REGENERATION INDUCED BY LOCAL DELIVERY OF BONE MORPHOGENETIC PROTEIN 2 FROM PRO-ANGIOGENIC NEAR-INFRARED-RESPONSIVE HYDROGELS

Withaferin A (WA) and celastrol (CEL) are major bioactive components of plants that have been widely employed in traditional medicine. The pleiotropic activities of plant preparations and the isolated compounds in vitro and in vivo have been documented in hundreds of studies. Both WA and CEL were shown to have anticancer activity. Although WA and CEL belong to different chemical classes, our synthesis of the available information suggests that the compounds share basic mechanisms of action. Both WA and CEL bind covalently to numerous proteins, causing the partial unfolding of some of these proteins and of many bystander proteins. The resulting proteotoxic stress, when excessive, leads to cell death. Both WA and CEL trigger the activation of the unfolded protein response (UPR) which, if the proteotoxic stress persists, results in apoptosis mediated by the PERK/eIF-2/ATF4/CHOP pathway or another UPR-dependent pathway. Other mechanisms of cell death may play contributory or even dominant roles depending on cell type. As shown in a proteomic study with WA, the compounds appear to function largely as electrophilic reactants, indiscriminately modifying reachable nucleophilic amino acid side chains of proteins. However, a remarkable degree of target specificity is imparted by the cellular context.

Exposure of many cancer cells, including multiple myeloma cells, to cytotoxic concentrations of natural products celastrol and withaferin A or synthetic compounds of the IHSF series resulted in denaturation of a luciferase reporter protein. Proteomic analysis of detergent-insoluble extract fractions from HeLa-derived cells revealed that withaferin A, IHSF058 and IHSF115 caused denaturation of 915, 722 and 991 of 5132 detected cellular proteins, respectively, of which 440 were targeted by all three compounds. Western blots showed that important fractions of these proteins, in some cases approaching half of total protein amounts, unfolded. Relatively indiscriminate covalent modification of target proteins was observed; 1178 different proteins were modified by IHSF058. Further illustrating the depth of the induced proteostasis crisis, only 13% of these proteins detectably aggregated, and 79% of the proteins that aggregated were not targets of covalent modification. Numerous proteostasis network components were modified and/or found in aggregates. Proteostasis disruption caused by the study compounds may be more profound than that mediated by proteasome inhibitors. The compounds act by a different mechanism that may be less susceptible to resistance development. Multiple myeloma cells were particularly sensitive to the compounds. Development of an additional proteostasis-disrupting therapy of multiple myeloma is suggested.

Current cranial repair techniques combine the use of autologous bone grafts and biomaterials. In addition to their association with harvesting morbidity, autografts are often limited by insufficient quantity of bone stock. Biomaterials lead to better outcomes, but their effectiveness is often compromised by the unpredictable lack of integration and structural failure. Bone tissue engineering offers the promising alternative of generating constructs composed of instructive biomaterials including cells or cell-secreted products, which could enhance the outcome of reconstructive treatments. This review focuses on cell-based approaches with potential to regenerate calvarial bone defects, including human studies and preclinical research. Further, we discuss strategies to deliver extracellular matrix, conditioned media and extracellular vesicles derived from cell cultures. Recent advances in 3D printing and bioprinting techniques that appear to be promising for cranial reconstruction are also discussed. Finally, we review cell-based gene therapy approaches, covering both unregulated and regulated gene switches that can create spatiotemporal patterns of transgenic therapeutic molecules. In summary, this review provides an overview of the current developments in cell-based strategies with potential to enhance the surgical armamentarium for regenerating cranial vault defects.