Readministration of high-dose adeno-associated virus gene therapy vectors enabled by ImmTOR nanoparticles combined with B cell-targeted agents.

Tolerogenic ImmTOR nanoparticles encapsulating rapamycin have been demonstrated to mitigate immunogenicity of adeno-associated virus (AAV) gene therapy vectors, enhance levels of transgene expression, and enable redosing of AAV at moderate vector doses of 2 to 5E12 vg/kg. However, recent clinical trials have often pushed AAV vector doses 10-fold to 50-fold higher, with serious adverse events observed at the upper range. Here, we assessed combination therapy of ImmTOR with B cell-targeting drugs for the ability to increase the efficiency of redosing at high vector doses. The combination of ImmTOR with a monoclonal antibody against B cell activation factor (aBAFF) exhibited strong synergy leading to more than a 5-fold to 10-fold reduction of splenic mature B cells and plasmablasts while increasing the fraction of pre-/pro-B cells. In addition, this combination dramatically reduced anti-AAV IgM and IgG antibodies, thus enabling four successive AAV administrations at doses up to 5E12 vg/kg and at least two AAV doses at 5E13 vg/kg, with the transgene expression level in the latter case being equal to that observed in control animals receiving a single vector dose of 1E14 vg/kg. Similar synergistic effects were seen with a combination of ImmTOR and a Bruton's tyrosine kinase inhibitor, ibrutinib. These results suggest that ImmTOR could be combined with B cell-targeting agents to enable repeated vector administrations as a potential strategy to avoid toxicities associated with vector doses above 1E14 vg/kg.

Rapamycin nanoparticles increase the therapeutic window of engineered interleukin-2 and drive expansion of antigen-specific regulatory T cells for protection against autoimmune disease.

Interleukin-2 (IL-2) therapies targeting the high affinity IL-2 receptor expressed on regulatory T cells (Tregs) have shown promising therapeutic benefit in autoimmune diseases through nonselective expansion of pre-existing Treg populations, but are potentially limited by the inability to induce antigen-specific Tregs, as well as by dose-limiting activation of effector immune cells in settings of inflammation. We recently developed biodegradable nanoparticles encapsulating rapamycin, called ImmTOR, which induce selective immune tolerance to co-administered antigens but do not increase total Treg numbers. Here we demonstrate that the combination of ImmTOR and an engineered Treg-selective IL-2 variant (termed IL-2 mutein) increases the number and durability of total Tregs, as well as inducing a profound synergistic increase in antigen-specific Tregs when combined with a target antigen. We demonstrate that the combination of ImmTOR and an IL-2 mutein leads to durable inhibition of antibody responses to co-administered AAV gene therapy capsid, even at sub-optimal doses of ImmTOR, and provides protection in autoimmune models of type 1 diabetes and primary biliary cholangitis. Importantly, ImmTOR also increases the therapeutic window of engineered IL-2 molecules by mitigating effector immune cell expansion and preventing exacerbation of disease in a model of graft-versus-host-disease. At the same time, IL-2 mutein shows potential for dose-sparing of ImmTOR. Overall, these results establish that the combination of ImmTOR and an IL-2 mutein show synergistic benefit on both safety and efficacy to provide durable antigen-specific immune tolerance to mitigate drug immunogenicity and to treat autoimmune diseases.

Nonstoichiometry, Defect Chemistry and Oxygen Transport in Fe-Doped Layered Double Perovskite Cobaltite PrBaCo2-xFexO6-δ (x = 0-0.6) Membrane Materials.

Mixed conducting cobaltites PrBaCo2-xFexO6-δ (x = 0-0.6) with a double perovskite structure are promising materials for ceramic semi-permeable membranes for oxygen separation and purification due to their fast oxygen exchange and diffusion capability. Here, we report the results of the detailed study of an interplay between the defect chemistry, oxygen nonstoichiometry and oxygen transport in these materials as a function of iron doping. We show that doping leads to a systematic variation of both the thermodynamics of defect formation reactions and oxygen transport properties. Thus, iron doping can be used to optimize the performance of mixed conducting oxygen-permeable double perovskite membrane materials.

ImmTOR nanoparticles enhance AAV transgene expression after initial and repeat dosing in a mouse model of methylmalonic acidemia.

A major barrier to adeno-associated virus (AAV) gene therapy is the inability to re-dose patients due to formation of vector-induced neutralizing antibodies (Nabs). Tolerogenic nanoparticles encapsulating rapamycin (ImmTOR) provide long-term and specific suppression of adaptive immune responses, allowing for vector re-dosing. Moreover, co-administration of hepatotropic AAV vectors and ImmTOR leads to an increase of transgene expression even after the first dose. ImmTOR and AAV Anc80 encoding the methylmalonyl-coenzyme A (CoA) mutase (MMUT) combination was tested in a mouse model of methylmalonic acidemia, a disease caused by mutations in the MMUT gene. Repeated co-administration of Anc80 and ImmTOR was well tolerated and led to nearly complete inhibition of immunoglobulin (Ig)G antibodies to the Anc80 capsid. A more profound decrease of plasma levels of the key toxic metabolite, plasma methylmalonic acid (pMMA), and disease biomarker, fibroblast growth factor 21 (FGF21), was observed after treatment with the ImmTOR and Anc80-MMUT combination. In addition, there were higher numbers of viral genomes per cell (vg/cell) and increased transgene expression when ImmTOR was co-administered with Anc80-MMUT. These effects were dose-dependent, with the higher doses of ImmTOR providing higher vg/cell and mRNA levels, and an improved biomarker response. Combining of ImmTOR and AAV can not only block the IgG response against capsid, but it also appears to potentiate transduction and enhance therapeutic transgene expression in the mouse model.

Enhancement of the Tolerogenic Phenotype in the Liver by ImmTOR Nanoparticles.

ImmTOR biodegradable nanoparticles encapsulating rapamycin have been shown to induce a durable tolerogenic immune response to co-administered biologics and gene therapy vectors. Prior mechanism of action studies have demonstrated selective biodistribution of ImmTOR to the spleen and liver following intravenous (IV) administration. In the spleen, ImmTOR has been shown to induce tolerogenic dendritic cells and antigen-specific regulatory T cells and inhibit antigen-specific B cell activation. Splenectomy of mice resulted in partial but incomplete abrogation of the tolerogenic immune response induced by ImmTOR. Here we investigated the ability of ImmTOR to enhance the tolerogenic environment in the liver. All the major resident populations of liver cells, including liver sinusoidal endothelial cells (LSECs), Kupffer cells (KC), stellate cells (SC), and hepatocytes, actively took up fluorescent-labeled ImmTOR particles, which resulted in downregulation of MHC class II and co-stimulatory molecules and upregulation of the PD-L1 checkpoint molecule. The LSEC, known to play an important role in hepatic tolerance induction, emerged as a key target cell for ImmTOR. LSEC isolated from ImmTOR treated mice inhibited antigen-specific activation of ovalbumin-specific OT-II T cells. The tolerogenic environment led to a multi-pronged modulation of hepatic T cell populations, resulting in an increase in T cells with a regulatory phenotype, upregulation of PD-1 on CD4+ and CD8+ T cells, and the emergence of a large population of CD4-CD8- (double negative) T cells. ImmTOR treatment protected mice in a concanavalin A-induced model of acute hepatitis, as evidenced by reduced production of inflammatory cytokines, infiltrate of activated leukocytes, and tissue necrosis. Modulation of T cell phenotype was seen to a lesser extent after administration by empty nanoparticles, but not free rapamycin. The upregulation of PD-1, but not the appearance of double negative T cells, was inhibited by antibodies against PD-L1 or CTLA-4. These results suggest that the liver may contribute to the tolerogenic properties of ImmTOR treatment.

Enhancement of liver-directed transgene expression at initial and repeat doses of AAV vectors admixed with ImmTOR nanoparticles.

Systemic AAV (adeno-associated virus) gene therapy is a promising approach for the treatment of inborn errors of metabolism, but questions remain regarding its potency and durability. Tolerogenic ImmTOR nanoparticles encapsulating rapamycin have been shown to block the formation of neutralizing anti-capsid antibodies, thereby enabling vector re-administration. Here, we further demonstrate that ImmTOR admixed with AAV vectors also enhances hepatic transgene expression at the initial dose of AAV vector, independent of its effects on adaptive immunity. ImmTOR enhances AAV trafficking to the liver, resulting in increased hepatic vector copy numbers and transgene mRNA expression. Enhanced transgene expression occurs through a mechanism independent of the AAV receptor and cannot be replicated in vivo with free rapamycin or empty nanoparticles. The multipronged mechanism of ImmTOR action makes it an attractive candidate to enable more efficient transgene expression at first dose while simultaneously inhibiting adaptive responses against AAV to enable repeat dosing.

Novel Prefrontal Synthesis Intervention Improves Language in Children with Autism.

Prefrontal synthesis (PFS) is defined as the ability to juxtapose mental visuospatial objects at will. Paralysis of PFS may be responsible for the lack of comprehension of spatial prepositions, semantically-reversible sentences, and recursive sentences observed in 30 to 40% of individuals with autism spectrum disorder (ASD). In this report we present data from a three-year-long clinical trial of 6454 ASD children age 2 to 12 years, which were administered a PFS-targeting intervention. Tablet-based verbal and nonverbal exercises emphasizing mental-juxtaposition-of-objects were organized into an application called Mental Imagery Therapy for Autism (MITA). The test group included participants who completed more than one thousand exercises and made no more than one error per exercise. The control group was selected from the rest of participants by a matching procedure. Each test group participant was matched to the control group participant by age, gender, expressive language, receptive language, sociability, cognitive awareness, and health score at first evaluation using propensity score analysis. The test group showed a 2.2-fold improvement in receptive language score vs. control group (p < 0.0001) and a 1.4-fold improvement in expressive language (p = 0.0144). No statistically significant change was detected in other subscales not targeted by the exercises. These findings show that language acquisition improves after training PFS and that a further investigation of the PFS-targeting intervention in a randomized controlled study is warranted.

Synthetic vaccine particles for durable cytolytic T lymphocyte responses and anti-tumor immunotherapy.

We previously reported that synthetic vaccine particles (SVP) encapsulating antigens and TLR agonists resulted in augmentation of immune responses with minimal production of systemic inflammatory cytokines. Here we evaluated two different polymer formulations of SVP-encapsulated antigens and tested their ability to induce cytolytic T lymphocytes (CTL) in combination with SVP-encapsulated adjuvants. One formulation led to efficient antigen processing and cross-presentation, rapid and sustained CTL activity, and expansion of CD8+ T cell effector memory cells locally and centrally, which persisted for at least 1-2 years after a single immunization. SVP therapeutic dosing resulted in suppression of tumor growth and a substantial delay in mortality in several syngeneic mouse cancer models. Treatment with checkpoint inhibitors and/or cytotoxic drugs, while suboptimal on their own, showed considerable synergy with SVP immunization. SVP encapsulation of endosomal TLR agonists provided superior CTL induction, therapeutic benefit and/or improved safety profile compared to free adjuvants. SVP vaccines encapsulating mutated HPV-16 E7 and E6/E7 recombinant proteins led to induction of broad CTL activity and strong inhibition of TC-1 tumor growth, even when administered therapeutically 13-14 days after tumor inoculation in animals bearing palpable tumors. A pilot study in non-human primates showed that SVP-encapsulated E7/E6 adjuvanted with SVP-encapsulated poly(I:C) led to robust induction of antigen-specific T and B cell responses.

Selective-versus-Standard Poststent Dilation for Carotid Artery Disease: A Systematic Review and Meta-Analysis.

BACKROUND: The safety and efficacy of standard poststent angioplasty in patients undergoing carotid artery stent placement have not been well-established. PURPOSE: We conducted a systematic review of the literature to evaluate the safety and efficacy of carotid artery stent placement and analyzed outcomes of standard-versus-selective poststent angioplasty. DATA SOURCES: A systematic search of MEDLINE, EMBASE, Scopus, and the Web of Science was performed for studies published between January 2000 and January 2015. STUDY SELECTION: We included studies with >30 patients describing standard or selective poststent angioplasty during carotid artery stent placement. DATA ANALYSIS: A random-effects meta-analysis was used to pool the following outcomes: periprocedural stroke/TIA, procedure-related neurologic/cardiovascular morbidity/mortality, bradycardia/hypotension, long-term stroke at last follow-up, long-term primary patency, and technical success. DATA SYNTHESIS: We included 87 studies with 19,684 patients with 20,378 carotid artery stenoses. There was no difference in clinical (P = .49) or angiographic outcomes (P = .93) in carotid artery stent placement treatment with selective or standard poststent balloon angioplasty. Both selective and standard poststent angioplasty groups had a very high technical success of >98% and a low procedure-related mortality of 0.9%. There were no significant differences between both groups in the incidence of restenosis (P = .93) or procedure-related complications (P = .37). LIMITATIONS: No comparison to a patient group without poststent dilation could be performed. CONCLUSIONS: Our meta-analysis demonstrated no significant difference in angiographic and clinical outcomes among series that performed standard poststent angioplasty and those that performed poststent angioplasty in only select patients.

Hemodynamic changes in a middle cerebral artery aneurysm at follow-up times before and after its rupture: a case report and a review of the literature.

Hemodynamic parameters play a significant role in the development of cerebral aneurysms. Parameters such as wall shear stress (WSS) or velocity could change in time and may contribute to aneurysm growth and rupture. However, the hemodynamic changes at the rupture location remain unclear because it is difficult to obtain data prior to rupture. We analyzed a case of a ruptured middle cerebral artery (MCA) aneurysm for which we acquired imaging data at three time points, including at rupture. A patient with an observed MCA aneurysm was admitted to the emergency department with clinical symptoms of a subarachnoid hemorrhage. During three-dimensional (3D) digital subtraction angiography (DSA), the aneurysm ruptured again. Imaging data from two visits before rupture and this 3D DSA images at the moment of rupture were acquired, and computational fluid dynamic (CFD) simulations were performed. Results were used to describe the time-dependent changes of the hemodynamic variables associated with rupture. Time-dependent hemodynamic changes at the rupture location were characterized by decreased WSS and flow velocity magnitude. The impingement jet in the dome changed its position in time and the impingement area at follow-up moved near the rupture location. The results suggest that the increased WSS on the dome and increased low wall shear stress area (LSA) and decreased WSS on the daughter bleb with slower flow and slow vortex may be associated with rupture. CFD performed during the follow-up period may be part of diagnostic tools used to determine the risk of aneurysm rupture.

Current Trends and Results of Endovascular Treatment of Unruptured Intracranial Aneurysms at a Single Institution in the Flow-Diverter Era.

BACKGROUND AND PURPOSE: During the past several years, the number of unruptured aneurysms treated with endovascular techniques has increased. Traditionally, coil embolization was the treatment of choice for these lesions; however, recently flow diversion has become a viable, and in some cases superior, treatment option. The current single-center study presents results and trends of endovascular treatment with flow diversion and coil embolization in an unselected group of patients with unruptured intracranial aneurysms in a "real world" setting during the flow-diverter era. MATERIALS AND METHODS: Three hundred ten patients with 318 treated unruptured aneurysms from June 2009 to May 2015 were included. Patient demographics, clinical characteristics, aneurysm/treatment characteristics, and outcomes were collected prospectively. We studied the following: intensive care unit admission/reasons, perioperative and mid-/long-term complications, target aneurysm rupture, retreatment/recurrence rates, and long-term neurologic outcome using the mRS. RESULTS: The flow-diverter group had a larger mean aneurysm size (12.3 ± 8.6 mm versus 8.7 ± 6.3 mm, P < .0001). There were no significant differences in the immediate (P = .43) and mid-/long-term complication rates (P = .54) between groups. Periprocedural neurologic morbidity and mortality rates were 2.1% and 0.5% in the coiling group and 2.5% and 1.6% in the flow-diverter group. Patients with coiling were more likely to be retreated than those with flow diversion (14.8% versus 5.7%, P = .009). Worsening of the mRS due to the target aneurysm was noted in only 3.2% of patients. CONCLUSIONS: The endovascular treatment of unruptured aneurysms can be performed with very low rates of neurologic complications. Both flow-diverter and coil therapy were safe and effective.

Brainstem cavernous malformations.

Of all cavernous malformations (CMs), 4% to 35% are found in the brainstem accounting for 13% of vascular malformations of the posterior fossa. The annual risk of hemorrhage associated with a CM with no history of a previous hemorrhagic episode is very low ranging from 0.6% to 1.1% per year. However, the risk of recurrent hemorrhage after a presenting bleed is significantly higher. There is a correlation between the extent of persistent neurological deficits and the number of recurrent hemorrhages as rehemorrhage increases the rate and severity of neurological deficits. Neurological deficits often improve after a hemorrhagic event spontaneously and sometimes resolve completely. The indication for surgery in patients with brainstem CMs is controversial. Over the years, we have taken a more cautious stance and we often recommend observation in patients after a single symptomatic bleed as most patients return to a good level of functioning after a single bleed. Surgery is recommended for more aggressive lesions usually after a recurrent bleed. In general, given the very low risk of bleeding from truly asymptomatic lesions, surgery should not be considered in these patients. For symptomatic lesions which have presented with hemorrhage, the decision of whether or not to proceed with surgical resection is related to the risk of surgery, patient's disposition and perceived risk of rebleeding. Favorable outcome can be achieved through surgical resection after an appropriate selection of the patients and thorough preoperative surgical planning.

Adjuvant-carrying synthetic vaccine particles augment the immune response to encapsulated antigen and exhibit strong local immune activation without inducing systemic cytokine release.

Augmentation of immunogenicity can be achieved by particulate delivery of an antigen and by its co-administration with an adjuvant. However, many adjuvants initiate strong systemic inflammatory reactions in vivo, leading to potential adverse events and safety concerns. We have developed a synthetic vaccine particle (SVP) technology that enables co-encapsulation of antigen with potent adjuvants. We demonstrate that co-delivery of an antigen with a TLR7/8 or TLR9 agonist in synthetic polymer nanoparticles results in a strong augmentation of humoral and cellular immune responses with minimal systemic production of inflammatory cytokines. In contrast, antigen encapsulated into nanoparticles and admixed with free TLR7/8 agonist leads to lower immunogenicity and rapid induction of high levels of inflammatory cytokines in the serum (e.g., TNF-a and IL-6 levels are 50- to 200-fold higher upon injection of free resiquimod (R848) than of nanoparticle-encapsulated R848). Conversely, local immune stimulation as evidenced by cellular infiltration of draining lymph nodes and by intranodal cytokine production was more pronounced and persisted longer when SVP-encapsulated TLR agonists were used. The strong local immune activation achieved using a modular self-assembling nanoparticle platform markedly enhanced immunogenicity and was equally effective whether antigen and adjuvant were co-encapsulated in a single nanoparticle formulation or co-delivered in two separate nanoparticles. Moreover, particle encapsulation enabled the utilization of CpG oligonucleotides with the natural phosphodiester backbone, which are otherwise rapidly hydrolyzed by nucleases in vivo. The use of SVP may enable clinical use of potent TLR agonists as vaccine adjuvants for indications where cellular immunity or robust humoral responses are required.

Importance of mRNA secondary structural elements for the expression of influenza virus genes.

Development of novel vaccines and therapeutics often requires efficient expression of recombinant viral proteins. Here we show that mutations in essential functional regions of conserved influenza proteins NP and NS1, lead to reduced expression of these genes in vitro. According to in silico analysis, these mRNA regions possess distinct secondary structures sensitive to mutations. We identified a novel structural feature within a region in NS1 mRNA that encodes amino acids essential for NS1 function. Mutations altering this mRNA element lead to significantly reduced protein expression. Conversely, expression was not affected by mutations resulting in amino acid substitutions, when they were designed to preserve this secondary RNA structural element. Furthermore, altering this structure significantly reduced RNA transcription without affecting mRNA stability. Therefore, distinct internal secondary structures of viral mRNA may be important for viral gene expression. If such elements encode amino acids essential for the protein function, then early selection against mutations in this region will be beneficial for the virus. This might point at yet another mechanism of viral evolution, especially for RNA viruses. Finally, introducing mutations into viral genes while preserving their secondary RNA structure, suggests a new method for the generation of efficiently expressed recombinants of viral proteins.

Effective expression of recombinant cytotoxic protein via its attachment to a polyglutamine domain.

Inadvertent cytotoxicity may hinder the expression of many recombinant proteins that are of industrial or medicinal importance. Here, we show that covalent binding of the influenza A cytotoxic protein M2 to a polyglutamine domain (polyQ-M2; QM2) results in significant delay of its cytotoxic effects when compared to wild-type protein (M2wt). We also show that while expression of recombinant M2wt from A/WSN/1933 strain could not be attained in vaccinia virus (VV), polyQ-M2 was successfully expressed in this system. Moreover, we demonstrate that in cell culture, the polyQ domain is cleaved off following 48 h of expression, thus releasing free and active M2. Similarly, we show the spontaneous cleavage and polyQ release from fusion with another distinct polypeptide, green fluorescent protein (GFP). Expression of M2 from QM2 construct was more prolonged than one based on M2wt-expressing construct, markedly exceeding it at the later time points. Therefore, cell death caused by a toxic polypeptide may be suppressed via genetic fusion with polyQ, resulting in its enhanced expression, followed by slow release of the free polypeptide from the fusion. Collectively, covalent fusion with polyQ or other aggregate-forming domains presents a novel approach for industrial production of cytotoxic proteins and also holds promise for gene therapy applications.

Development of a vaccine against pandemic influenza viruses: current status and perspectives.

The constant threat of a new influenza pandemic, which may be caused by a highly pathogenic avian influenza virus, necessitates the development of a vaccine capable of providing efficient, long-term, and cost-effective protection. Proven avenues for the development of vaccines against seasonal influenza as well as novel approaches have been explored over the past decade. Whereas significant insights are consistently being made, the generation of a highly efficient and cross-protective vaccine against the future pandemic influenza strain remains as the ultimate goal in the field. In this review, we re-examine these efforts and outline the scientific, political, and economic problems that befall this area of biotechnological research.

The proteosomal degradation of fusion proteins cannot be predicted from the proteosome susceptibility of their individual components.

It is assumed that the proteosome-processing characteristics of fusion constructs can be predicted from the sum of the proteosome sensitivity of their components. In the present study, we observed that a fusion construct consisting of proteosome-degradable proteins does not necessarily result in a proteosome-degradable chimera. Conversely, fusion of proteosome-resistant proteins may result in a proteosome-degradable composite. We previously demonstrated that conserved influenza proteins can be unified into a single fusion antigen that is protective, and that vaccination with combinations of proteosome-resistant and proteosome-degradable antigens resulted in an augmented T-cell response. In the present study we constructed proteosome-degradable mutants of conserved influenza proteins NP, M1, NS1, and M2. These were then fused into multipartite proteins in different positions. The stability and degradation profiles of these fusion constructs were demonstrated to depend on the relative position of the individual proteins within the chimeric molecule. Combining unstable sequences of either NP and M1 or NS1 and M2 resulted in either rapidly proteosome degraded or proteosome-resistant bipartite fusion mutants. However, further unification of the proteosome-degradable forms into a single four-partite fusion molecule resulted in relatively stable chimeric proteins. Conversely, the addition of proteosome-resistant wild-type M2 to proteosome-resistant NP-M1-NS1 fusion protein lead to the decreased stability of the resulting four-partite multigene products, which in one case was clearly proteosome dependent. Additionally, a highly destabilized form of M1 failed to destabilize the wild-type NP. Collectively, we did not observe any additive effect leading to proteosomal degradation/nondegradation of a multigene construct.

Inhibition of influenza M2-induced cell death alleviates its negative contribution to vaccination efficiency.

The effectiveness of recombinant vaccines encoding full-length M2 protein of influenza virus or its ectodomain (M2e) have previously been tested in a number of models with varying degrees of success. Recently, we reported a strong cytotoxic effect exhibited by M2 on mammalian cells in vitro. Here we demonstrated a decrease in protection when M2 was added to a DNA vaccination regimen that included influenza NP. Furthermore, we have constructed several fusion proteins of conserved genes of influenza virus and tested their expression in vitro and protective potential in vivo. The four-partite NP-M1-M2-NS1 fusion antigen that has M2 sequence engineered in the middle part of the composite protein was shown to not be cytotoxic in vitro. A three-partite fusion protein (consisting of NP, M1 and NS1) was expressed much more efficiently than the four-partite protein. Both of these constructs provided statistically significant protection upon DNA vaccination, with construct NP-M1-M2-NS1 being the most effective. We conclude that incorporation of M2 into a vaccination regimen may be beneficial only when its apparent cytotoxicity-linked negative effects are neutralized. The possible significance of this data for influenza vaccination regimens and preparations is discussed.

Colloidal aspects relating to direct incorporation of TiO2 nanoparticles into mesoporous spheres by an aerosol-assisted process.

Titania nanoparticles have been incorporated into spherical mesoporous silica powders by an aerosol-assisted synthesis process from both aqueous and ethanol-based precursor dispersions. Transmission electron microscopy (TEM) showed that the titania nanoparticles exist as single particles or small aggregates within the mesoporous carrier particles and analysis of the nitrogen adsorption isotherms proved that the pore blocking of the particles is small. Particle size and zeta potential measurements showed that the addition of tetraethoxysiloxane (TEOS), and also hexadecyl trimethyl ammonium bromide (C16TAB) induced flocculation of the TiO2 nanoparticles. The higher yield and narrower size distribution of the composite powder produced from ethanol-based dispersions compared to the aqueous dispersions could be related to a smaller degree of aggregation, indicated by rheological measurements.