Browsing by Author "Lemmer, Yolandy"

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In vivo evaluation of the biodistribution and safety of PLGA nanoparticles as drug delivery systems
(Elsevier Inc., 2010-10) Semete, Boitumelo; Booysen, Laetitia; Lemmer, Yolandy; Kalombo, Lonji; Katata, Lebogang; Verschoor, Jan
The remarkable physicochemical properties of particles in the nanometer range have been proven to address many challenges in the field of science. However, the possible toxic effects of these particles have raised some concerns. The aim of this article is to evaluate the effects of poly(lactide-co-glycolide) (PLGA) nanoparticles in vitro and in vivo compared to industrial nanoparticles of a similar size range such as zinc oxide, ferrous oxide, and fumed silica. An in vitro cytotoxicity study was conducted to assess the cell viability following exposure to PLGA nanoparticles. Viability was determined by means of a WST assay, wherein cell viability of greater than 75% was observed for both PLGA and amorphous fumed silica particles and ferrous oxide, but was significantly reduced for zinc oxide particles. In vivo toxicity assays were performed via histopathological evaluation, and no specific anatomical pathological changes or tissue damage was observed in the tissues of Balb/C mice. The extent of tissue distribution and retention following oral administration of PLGA particles was analyzed for 7 days. After 7 days, the particles remained detectable in the brain, heart, kidney, liver, lungs, and spleen. The results show that a mean percentage (40.04%) of the particles were localized in the liver, 25.97% in the kidney, and 12.86% in the brain. The lowest percentage was observed in the spleen. Thus, based on these assays, it can be concluded that the toxic effects observed with various industrial nanoparticles will not be observed with particles made of synthetic polymers such as PLGA when applied in the field of nanomedicine. Furthermore, the biodistribution of the particles warrants surface modification of the particles to avoid higher particle localization in the liver. From the clinical editor: The aim of this study was to evaluate the effects of poly(lactide-co-glycolide) (PLGA) nanoparticles in vitro and in vivo compared to industrial nanoparticles including zinc oxide, ferrous oxide, and fumed silica. The authors concluded that the toxic effects observed with various industrial nanoparticles is unlikely to be observed with particles made of PLGA. The biodistribution of these particles warrants surface modification to avoid particle accumulation in the liver.
Mycolic acids, a promising mycobacterial ligand for targeting of nanoencapsulated drugs in tuberculosis
(Elsevier, 2015-06-06) Lemmer, Yolandy; Kalombo, Lonji; Pietersen, Ray-Dean; Jones, Arwyn T.; Semete-Makokotlela, Boitumelo; Van Wyngaardt, Sandra; Ramalapa, Bathabile; Stoltz, Anton C.; Baker, Bienyameen; Verschoor, Jan A.; Swai, Hulda; de Chastellier, Chantal
The appearance of drug-resistant strains of Mycobacterium tuberculosis (Mtb) poses a great challenge to the development of novel treatment programmes to combat tuberculosis. Since innovative nanotechnologiesmight alleviate the limitations of current therapies, we have designed a new nanoformulation for use as an anti-TB drug delivery system. It consists of incorporating mycobacterial cellwallmycolic acids (MA) as targeting ligands into a drug-encapsulating Poly DL-lactic-co-glycolic acid polymer (PLGA), via a double emulsion solvent evaporation technique. Bonemarrow-derivedmousemacrophages, either uninfected or infectedwith differentmycobacterial strains (Mycobacterium avium, Mycobacterium bovis BCG or Mtb), were exposed to encapsulated isoniazid-PLGA nanoparticles (NPs) using MA as a targeting ligand. The fate of the NPs was monitored by electron microscopy. Our study showed that i) the inclusion of MA in the nanoformulations resulted in their expression on the outer surface and a significant increase in phagocytic uptake of the NPs; ii) nanoparticle-containing phagosomes were rapidly processed into phagolysosomes, whether MA had been included or not; and iii) nanoparticlecontaining phagolysosomes did not fuse with non-matured mycobacterium-containing phagosomes, but fusion events with mycobacterium-containing phagolysosomes were clearly observed.
Spray-Dried, Nanoencapsulated, Multi-Drug Anti-Tuberculosis Therapy Aimed at OnceWeekly Administration for the Duration of Treatment
(MDPI, 2019-08-15) Kalombo, Lonji; Lemmer, Yolandy; Semete-Makokotlela, Boitumelo; Ramalapa, Bathabile; Nkuna, Patric; Booysen, Laetitia; Naidoo, Saloshnee; Hayeshi, Rose; Verschoor, Jan; Swai, Hulda
Aiming to improve the treatment outcomes of current daily tuberculosis (TB) chemotherapy over several months, we investigated whether nanoencapsulation of existing drugs would allow decreasing the treatment frequency to weekly, thereby ultimately improving patient compliance. Nanoencapsulation of three first-line anti-TB drugs was achieved by a unique, scalable spray-drying technology forming free-flowing powders in the nanometer range with encapsulation e ciencies of 82, 75, and 62% respectively for rifampicin, pyrazinamide, and isoniazid. In a pre-clinical study on TB infected mice, we demonstrate that the encapsulated drugs, administered once weekly for nine weeks, showed comparable e cacy to daily treatment with free drugs over the same experimental period. Both treatment approaches had equivalent outcomes for resolution of inflammation associated with the infection of lungs and spleens. These results demonstrate how scalable technology could be used to manufacture nanoencapsulated drugs. The formulations may be used to reduce the oral dose frequency from daily to once weekly in order to treat uncomplicated TB.
State of the art and future directions in nanomedicine for tuberculosis.
(Expert Opinion on Drug Delivery, 2013-12-01) Dube, Admire; Lemmer, Yolandy; Hayeshi, Rose; Balogun, Mohammed; Labuschagne, Philip; Swai, Hulda; Kalombo, Lonji
Introduction: Tuberculosis (TB) ranks the second leading cause of death from an infectious disease worldwide. However, treatment of TB is affected by poor patient compliance due to the requirement for daily drug administration, for lengthy periods of time, often with severe drug-induced side effects. Nanomedicines have the potential to improve treatment outcomes by providing therapies with reduced drug doses, administered less frequently, under shortened treatment durations. Areas covered: In this article, we present the pathophysiology of the disease, focusing on pulmonary TB and the characteristics of drugs used in treatment and discuss the application of nanomedicines within this scope. We also discuss new formulation approaches for TB nanomedicines and directions for future research. Expert opinion: Nanomedicines have the potential to improve TB treatment outcomes. New approaches such as nanoparticle systems able to impact the immune response of macrophages and deliver drug intracellularly, as well as the use of polymer–drug conjugates for drug delivery, are likely to play an important role in TB nanomedicines in future. However, further research is required before TB nanomedicines can be translated to the clinic.