1
|
Osorio M, Martinez E, Naranjo T, Castro C. Recent Advances in Polymer Nanomaterials for Drug Delivery of Adjuvants in Colorectal Cancer Treatment: A Scientific-Technological Analysis and Review. Molecules 2020; 25:E2270. [PMID: 32408538 PMCID: PMC7288015 DOI: 10.3390/molecules25102270] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 12/22/2022] Open
Abstract
Colorectal cancer (CRC) is the type with the second highest morbidity. Recently, a great number of bioactive compounds and encapsulation techniques have been developed. Thus, this paper aims to review the drug delivery strategies for chemotherapy adjuvant treatments for CRC, including an initial scientific-technological analysis of the papers and patents related to cancer, CRC, and adjuvant treatments. For 2018, a total of 167,366 cancer-related papers and 306,240 patents were found. Adjuvant treatments represented 39.3% of the total CRC patents, indicating the importance of adjuvants in the prognosis of patients. Chemotherapy adjuvants can be divided into two groups, natural and synthetic (5-fluorouracil and derivatives). Both groups can be encapsulated using polymers. Polymer-based drug delivery systems can be classified according to polymer nature. From those, anionic polymers have garnered the most attention, because they are pH responsive. The use of polymers tailors the desorption profile, improving drug bioavailability and enhancing the local treatment of CRC via oral administration. Finally, it can be concluded that antioxidants are emerging compounds that can complement today's chemotherapy treatments. In the long term, encapsulated antioxidants will replace synthetic drugs and will play an important role in curing CRC.
Collapse
Affiliation(s)
- Marlon Osorio
- School of Engineering, Universidad Pontificia Bolivariana, Circular 1 # 70-01, Medellín 050031, Colombia; (M.O.); (E.M.)
| | - Estefanía Martinez
- School of Engineering, Universidad Pontificia Bolivariana, Circular 1 # 70-01, Medellín 050031, Colombia; (M.O.); (E.M.)
| | - Tonny Naranjo
- School of Health Sciences, Universidad Pontificia Bolivariana, Calle 78 B # 72 A-109, Medellín 050034, Colombia;
- Medical and Experimental Mycology Group, Corporación para Investigaciones Biológicas, Carrera 72 A # 78 B-141, Medellín 050034, Colombia
| | - Cristina Castro
- School of Engineering, Universidad Pontificia Bolivariana, Circular 1 # 70-01, Medellín 050031, Colombia; (M.O.); (E.M.)
| |
Collapse
|
2
|
Bhattacharya S, Dineshkumar R, Dhanarajan G, Sen R, Mishra S. Improvement of ε-polylysine production by marine bacterium Bacillus licheniformis using artificial neural network modeling and particle swarm optimization technique. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2017.06.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
3
|
Morgan AJL, Hidalgo San Jose L, Jamieson WD, Wymant JM, Song B, Stephens P, Barrow DA, Castell OK. Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication. PLoS One 2016; 11:e0152023. [PMID: 27050661 PMCID: PMC4822857 DOI: 10.1371/journal.pone.0152023] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/08/2016] [Indexed: 11/24/2022] Open
Abstract
The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components.
Collapse
Affiliation(s)
- Alex J. L. Morgan
- Cardiff School of Engineering, Cardiff University, Queen’s Building, The Parade, Cardiff, CF24 3AA, United Kingdom
- * E-mail:
| | - Lorena Hidalgo San Jose
- Cardiff School of Engineering, Cardiff University, Queen’s Building, The Parade, Cardiff, CF24 3AA, United Kingdom
- Oral and Biomedical Sciences, Cardiff Institute of Tissue Engineering and Repair, School of Dentistry, Cardiff University, Heath Park, Cardiff, CF14 4XY, United Kingdom
| | - William D. Jamieson
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Ave, Cardiff, CF10 3NB, United Kingdom
| | - Jennifer M. Wymant
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Ave, Cardiff, CF10 3NB, United Kingdom
| | - Bing Song
- Oral and Biomedical Sciences, Cardiff Institute of Tissue Engineering and Repair, School of Dentistry, Cardiff University, Heath Park, Cardiff, CF14 4XY, United Kingdom
| | - Phil Stephens
- Oral and Biomedical Sciences, Cardiff Institute of Tissue Engineering and Repair, School of Dentistry, Cardiff University, Heath Park, Cardiff, CF14 4XY, United Kingdom
| | - David A. Barrow
- Cardiff School of Engineering, Cardiff University, Queen’s Building, The Parade, Cardiff, CF24 3AA, United Kingdom
| | - Oliver K. Castell
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Ave, Cardiff, CF10 3NB, United Kingdom
| |
Collapse
|
4
|
Walters AA, Krastev C, Hill AVS, Milicic A. Next generation vaccines: single-dose encapsulated vaccines for improved global immunisation coverage and efficacy. ACTA ACUST UNITED AC 2015; 67:400-8. [PMID: 25644530 DOI: 10.1111/jphp.12367] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 11/09/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Vaccination is considered the most successful health intervention; yet incomplete immunisation coverage continues to risk outbreaks of vaccine preventable diseases worldwide. Vaccination coverage improvement through a single-dose prime-boost technology would revolutionise modern vaccinology, impacting on disease prevalence, significantly benefiting health care and lowering economic burden of disease. KEY FINDINGS Over the past 30 years, there have been efforts to develop a single-dose delayed release vaccine technology that could replace the repeated prime-boost immunisations required for many current vaccines. Biocompatible polymers have been employed to encapsulate model vaccines for delayed delivery in vivo, using either continuous or pulsed release. Biomaterial considerations, safety aspects, particle characteristics and immunological aspects of this approach are discussed in detail. SUMMARY Despite many studies showing the feasibility of vaccine encapsulation for single-dose prime-boost administration, none have been translated into convincing utility in animal models or human trials. Further development of the encapsulation technology, through optimising the particle composition, formulation, antigen loading efficacy and stability, could lead to the application of this important approach in vaccine deployment. If successful, this would provide a solution to better global vaccination coverage through a reduction in the number of immunisations needed to achieve protection against infectious diseases. This review provides an overview of single-dose vaccination in the context of today's vaccine needs and is derived from a body of literature that has not been reviewed for over a decade.
Collapse
Affiliation(s)
- Adam A Walters
- ORCRB, The Jenner Institute, University of Oxford, Oxford, UK
| | | | | | | |
Collapse
|
5
|
|
6
|
Batubara I, Rahayu D, Mohamad K, Prasetyaningtyas WE. Leydig Cells Encapsulation with Alginate-Chitosan: Optimization of Microcapsule Formation. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jeas.2012.22003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
7
|
Abstract
The development of drug-delivering nanoparticles from natural materials for various biomedical applications is an area of great promise. However, the contradictory data on their uncontrollable diameter, unstable structure and toxic effects, highlight the need to study their preparation, characterization and cytotoxic effects in cells. In this work, nanocapsules are made from a type of W/O microemulsion system with low-molecular-weight alginate (LMWALG) and oligochitosan (OCS). The particles possess excellent biocompatibility and good biodegradability. The size of capsules is controlled and optimized by carefully adjusting the molecular weight and concentration of LMWALG and OCS. We found, from orthogonal experiments, the encapsulation time leading to a uniform size distribution with an average diameter of 136 nm. Furthermore, we found that molecular weights of LMWALG and OCS significantly influence the stability and size of capsules. The optimized nanocapsules are further used to study the drug release of BSA. Results show that the efficiency of encapsulation approximately reaches 88.4% and the concentration of BSA in phosphate-buffered solution (PBS, pH = 7.4) is well maintained at a level of 35 to 40% from 12 h to 48 h, due to the stable and slow degradation of the nanocapusules. The biocompatibility of LMWALG/OCS nanocapsules is cross-examined by cytotoxicity experiments and acute systemic toxicological tests, and they were found to enhance the survival rate of the cells from 80.30 to 95.39% in 7 days. The synthesized nanocapsules exhibit high biocompatibility, non-toxicity, biodegradation, and uniform size, providing a new potential candidate for drug releases in clinic experiments.
Collapse
Affiliation(s)
- Ting Wang
- Chien-Shiung Wu Laboratory, Southeast University, Nanjing, MD 210096, China
| | | |
Collapse
|
8
|
|
9
|
Abstract
The shortage of donors for organ transplantation has stimulated research on stem cells as a potential resource for cell-based therapy in all human tissues. Stem cells have been used for regenerative medicine applications in many organ systems, including the genitourinary system. The potential applications for stem cell therapy have, however, been restricted by the ethical issues associated with embryonic stem cell research. Instead, scientists have explored other cell sources, including progenitor and stem cells derived from adult tissues and stem cells derived from the amniotic fluid and placenta. In addition, novel techniques for generating stem cells in the laboratory are being developed. These techniques include somatic cell nuclear transfer, in which the nucleus of an adult somatic cell is placed into an oocyte, and reprogramming of adult cells to induce stem-cell-like behavior. Such techniques are now being used in tissue engineering applications, and some of the most successful experiments have been in the field of urology. Techniques to regenerate bladder tissue have reached the clinic, and exciting progress is being made in other areas, such as regeneration of the kidney and urethra. Cell therapy as a treatment for incontinence and infertility might soon become a reality. Physicians should be optimistic that regenerative medicine and tissue engineering will one day provide mainstream treatment options for urologic disorders.
Collapse
|
10
|
Abstract
Polymeric microcapsules have been widely investigated for protein delivery. Common problems include: low stability, low encapsulation efficiency, lack of uniformity, and burst release. Cyclodextrins (CDs) are known to enhance stability and solubility of proteins in solution. This research examines the effect of alpha-, beta-, and gamma-CDs on: (1) stability, (2) encapsulation, and (3) release of insulin from ethylcellulose microcapsules. All CDs improved thermal stability of insulin by lowering the enthalpy of unfolding by 16-52%. alpha- and gamma-CDs also increased the encapsulation efficiency of insulin and improved uniformity of the microcapsule formulations. Two mathematical models were proposed to account for insulin release and consisted of multiple zero order and first order input processes, and a single first order output process. All CDs decreased the initial burst release of insulin by up to 30%. This research demonstrates the potential for CDs to improve stability, uniformity, and encapsulation of proteins in microcapsule formulations.
Collapse
Affiliation(s)
- R L Graves
- University of the Sciences in Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | | | | |
Collapse
|
11
|
Bajpai AK, Bhanu S. Dynamics of controlled release of heparin from swellable crosslinked starch microspheres. J Mater Sci Mater Med 2007; 18:1613-21. [PMID: 17483909 DOI: 10.1007/s10856-007-3020-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 05/05/2006] [Indexed: 05/15/2023]
Abstract
The microspheres of crosslinked starch have been prepared and characterized by IR spectral analysis and SEM technique. The prepared microspheres were loaded with an anticoagulant drug 'heparin' and the kinetics of in-vitro release of heparin was investigated spectrophotometrically at physiological pH (7.4) and body temperature (37 degrees C). The influence of percent loading of heparin, chemical architecture of the microspheres and pH of the release medium were examined on the release profiles of the drug. The chemical stability of heparin was tested in phosphate buffer saline (pH 7.4) and the release was also studied in various simulated biological fluids.
Collapse
Affiliation(s)
- A K Bajpai
- Bose Memorial Research Laboratory, Department of Chemistry, Government Autonomous Science College, Jabalpur, MP 482001, India.
| | | |
Collapse
|
12
|
Ribeiro AJ, Silva C, Ferreira D, Veiga F. Chitosan-reinforced alginate microspheres obtained through the emulsification/internal gelation technique. Eur J Pharm Sci 2005; 25:31-40. [PMID: 15854798 DOI: 10.1016/j.ejps.2005.01.016] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2004] [Revised: 01/11/2005] [Accepted: 01/14/2005] [Indexed: 11/25/2022]
Abstract
Alginate microspheres prepared by emulsification/internal gelation were chosen as carriers for a model protein, hemoglobin (Hb). Reinforced chitosan-coated microspheres were obtained by an uninterrupted method, in order to simplify the coating process, minimize protein losses during production and to avoid Hb escape under acidic conditions. Microspheres recovery was evaluated as well as its morphology by determination of Hb encapsulation efficiency and microscopic observation, respectively. The formation of chitosan membrane made of it interaction with alginate was assessed by DSC (differential scanning calorimetry) and FT-IR (Fourier-transform infrared spectrometry) studies. Spherical uncoated microspheres with a mean diameter of 20 microm and encapsulation efficiency above 89% were obtained. Coated microspheres provided similar encapsulation efficiency but a higher mean diameter was obtained due to microspheres clumping during the coating step. Protein loss occurred mainly during emulsification rather than recovery. FT-IR and DSC together indicated electrostatic interactions between alginate carboxylate and chitosan ammonium groups as the main forces for complex formation. Hb release from microspheres showed a pH-dependent profile and was affected by chitosan coating. Under simulated gastric conditions, a total Hb burst release from uncoated microspheres was decreased with one-stage and two-stage chitosan coatings (68% and 28%, respectively). At pH 6.8, the Hb release from coated microspheres was fast but incomplete. These results suggest an optimization of the coating method to protect Hb under acidic conditions and to permit a complete but sustained release of Hb.
Collapse
Affiliation(s)
- António J Ribeiro
- Laboratório de Tecnologia Farmacêutica, Instituto Superior de Ciências da Saúde-Norte, 4585-116 Gandra, Portugal.
| | | | | | | |
Collapse
|
13
|
De Diego Rodríguez E, Villanueva Peña A, Roca Edreira A, Martín García B, Meana Infiesta A, Gómez Llames S. [Current status of tissue engineering in urology. Review of the literature]. Actas Urol Esp 2005; 28:636-45. [PMID: 16050197 DOI: 10.1016/s0210-4806(04)73154-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the eighties a new field of the medicine appears wich applies the principles of cellular cultivation to synthetic biodegradable polymers scaffolds with the purpose of creating autologous biological substitutes that could improve, maintain or restore the function of organs or damaged tissues. The Tissue Engineering constitutes a new discipline in full phase of development especially in USA, with multiple potential applications in several medical specialities. Our speciality can't remain indifferent to interest and encouraging future originated by this new science. In this work we have made a wide bibliographical revision in the Medline to know the antecedents, current state and the possible future applications of Tissue Engineering in Urology.
Collapse
|
14
|
Weber W, Rinderknecht M, Daoud-El Baba M, de Glutz FN, Aubel D, Fussenegger M. CellMAC: a novel technology for encapsulation of mammalian cells in cellulose sulfate/pDADMAC capsules assembled on a transient alginate/Ca2+ scaffold. J Biotechnol 2004; 114:315-26. [PMID: 15522441 DOI: 10.1016/j.jbiotec.2004.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Revised: 07/14/2004] [Accepted: 07/15/2004] [Indexed: 11/17/2022]
Abstract
Microencapsulation of desired mammalian cell phenotypes in biocompatible polymer matrices represents a powerful technology for cell-based therapies and biopharmaceutical manufacturing of protein therapeutics. We have pioneered a novel jet break-up-compatible process for encapsulation of mammalian cells in cellulose sulfate (CS)/poly-diallyl-dimethyl-ammoniumchloride (pDADMAC) (CellMAC) capsules. CS and pDADMAC polymerize on a transient ad hoc co-assembled Ca2+/alginate scaffold and form homogenous capsules following dissolution of the alginate core by Ca2+ chelating agents. CellMAC capsules exhibited excellent mechanical properties and showed a molecular weight cut-off between 43 and 77kDa. Chinese hamster ovary cells engineered for constitutive production of the glycohormone erythropoietin reached high viable cell densities when grown inside CellMAC capsules, while specific erythropoietin (EPO) productivities matched those of conventional non-encapsulated control cultures. CellMAC-encapsulated EPO-production cell lines induced increased EPO serum levels when implanted intraperitoneally into mice and provided robust glycoprotein production during standard stirred-tank bioreactor operation. We expect the CellMAC technology to foster advances in therapeutic encapsulation of engineered cell lines as well as manufacturing of protein pharmaceuticals.
Collapse
Affiliation(s)
- Wilfried Weber
- Institute of Biotechnology, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich, Switzerland
| | | | | | | | | | | |
Collapse
|
15
|
Affiliation(s)
- A Atala
- Department of Urology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
16
|
Abstract
A number of programmable rate-controlled drug delivery technologies have been developed during the last two decades with the aim of regulating the rate of drug delivery, sustaining the duration of therapeutic action and/or targeting the delivery of drug to a specific tissue. As a result, several therapeutically beneficial outcomes can be achieved, such as: (i) controlled delivery of a therapeutic dose at a desirable rate of delivery; (ii) maintenance of drug concentrations within an optimal therapeutic range for prolonged duration of treatment; (iii) maximisation of efficacy-dose relationship; (iv) reduction of adverse effects; (v) minimisation of the need for frequent dose intake; and (vi) enhancement of patient compliance. The treatment of illness can thus be optimised. To gain a better understanding of how to optimise the treatment of illnesses by applying programmable rate-controlled drug delivery technologies, this article reviews the scientific concepts and technical principles behind the development of various programmable rate-controlled drug delivery systems that have been marketed or are under active development. Finally, the roles of these technologies in optimising therapeutic outcomes in nine therapeutic areas are discussed.
Collapse
Affiliation(s)
- Yie W Chien
- College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | | |
Collapse
|
17
|
Abstract
AIM: To explore the anti-tumor immunity against CT26 colon tumor of the microencapsulated cells modified with murine interleukine-12 (mIL-12) gene.
METHODS: Mouse fibroblasts (NIH3T3) were stably transfected to express mIL-12 using expression plasmids carrying mIL-12 gene (p35 and p40), and NIH3T3-mIL-12 cells were encapsulated in alginate microcapsules for long-term delivery of mIL-12. mIL-12 released from the microencapsulated NIH3T3-mIL-12 cells was confirmed using ELISA assay. Transplantation of the microencapsulated NIH3T3-mIL-12 cells was performed in the tumor-bearing mice with CT26 cells. The anti-tumor responses and the anti-tumor activities of the microencapsulated NIH3T3-mIL-12 cells were evaluated.
RESULTS: Microencapsulated NIH3T3-mIL-12 cells could release mIL-12 continuously and stably for a long time. After the microencapsulated NIH3T3-mIL-12 cells were transplanted subcutaneously into the tumor-bearing mice for 21 d, the serum concentrations of mIL-12, mIL-2 and mIFN-γ, the cytotoxicity of the CTL from the splenocytes and the NK activity in the treatment group were significantly higher than those in the controls. Moreover, mIL-12 released from the microencapsulated NIH3T3-mIL-12 cells resulted in a significant inhibition of tumor proliferation and a prolonged survival of tumor-bearing mice.
CONCLUSION: The microencapsulated NIH3T3-mIL-12 cells have a significant therapeutic effect on the experimental colon tumor by activating anti-tumor immune responses in vivo. Microencapsulated and genetically engineered cells may be an extremely versatile tool for tumor gene therapy.
Collapse
Affiliation(s)
- Shu Zheng
- Cancer Institute, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
| | | | | | | | | |
Collapse
|
18
|
Abstract
Tissue engineering is a rather new field of science. Despite this fact, some experimental investigations have already been applied in clinical studies. Compared to other medical fields, tissue engineering in urology is well established. Tissue-engineered bulking agents and tissue-engineered bladder augments are being investigated in clinical trials. Even though the knowledge gained in recent years is promising, the results of cellular therapies need to be critically judged before being finally applied in patients. Genetic engineering and stem cell research (adult undifferentiated cells) have had major impact on the field of tissue engineering over the past 2 years. By using the technology of genetic engineering, biochemical and functional qualities of tissues may be modified. Adult stem cells may help to substitute lost tissue in an autologous fashion by isolating undifferentiated cells from the body and by differentiating them into a desired cell type. These cells may be used to form native functional tissue to replace a diseased organ or organ part.
Collapse
Affiliation(s)
- G Bartsch
- Abteilung für Urologie und Kinderurologie, Urologische Universitätsklinik und Poliklinik, Universität Ulm.
| | | |
Collapse
|
19
|
Abstract
Controlled release beads were prepared by using alginate (ALG), konjac glucomannan (KGM) and chitosan (CHI). Bovine serum albumin and insulin were used as model proteins for in vitro assessments. It was observed that KGM could be contained within beads, and faintness hydrogen binding and electrostatic interaction exist between ALG and KGM by infrared spectra. Clear dents were found on the surface of beads using KGM by scanning electron microscopy. Use of KGM could help increase the payload of drug. After beads were treated by 0.1 N HCl for 4 h and put into pH 7.4 buffers, protein was released from ALG-CHI beads within 1 h, while it was lost from ALG-KGM-CHI beads for 3 h. However, the leaking of protein from ALG-KGM-CHI beads was also increased in 0.1 N HCl solution. Concentration of gelling ion had great effect on release rate and gel structure. Studies of water of hydration had shown that swelling of ALG-KGM-CHI beads was higher than that of ALG-CHI beads in acidic solution, but the opposite result was obtained in alkali solution. The result indicated that the diffusion of protein was related to the viscosity and swelling properties of KGM.
Collapse
Affiliation(s)
- Kang Wang
- Enzyme Technology Laboratory, Chemical Engineering Research Center, Tianjin University, Tianjin 300072, PR China
| | | |
Collapse
|
20
|
Abstract
The objectives of this study were to characterize the pharmacokinetics of vascular endothelial growth factor (VEGF) in poly(lactic-co-glycolic) acid (PLGA) microspheres using a rat model, and to develop a pharmacokinetic model for this controlled release formulation. 14C-VEGF was encapsulated using a solid-in-oil-in-water emulsification method. The microspheres were administered subcutaneously to rats and the pharmacokinetic parameters were compared with those of protein solutions. Intravenous administration of protein solutions resulted in short half-lives and subcutaneous administration resulted in rapid clearance from the subcutaneous tissue, with high plasma concentrations as expressed by rapid absorption and elimination. The subcutaneous administration of the VEGF microspheres produced low plasma concentrations and high subcutaneous concentrations over a period of 7 weeks. The area under the curve (AUC), the time required to achieve the maximum concentration (tmax), the maximum concentration (Cmax) in blood samples and the elimination rate constant (kel) values at the subcutaneous tissue site were selected to compare the pharmacokinetic characterization of VEGF microspheres with that of protein solutions. The in-vivo release profiles of the proteins were slower than the in-vitro release profiles and they followed the same trend as the in-vitro and in-vivo PLGA degradation rates. The PLGA microsphere degradation was the determinant step for VEGF release from the microspheres and its absorption at the subcutaneous site. Microspheres appear to be an attractive system for the localized rate-controlled delivery of VEGF. 14C-Methylation via reductive alkylation of VEGF did not affect its mitogenic activity, however approximately 25% activity was lost following release from PLGA microspheres. This loss of activity may be due to degradation in an acidic environment as a result of PLGA degradation.
Collapse
Affiliation(s)
- Tae-Kyoung Kim
- School of Pharmacy, University of Connecticut, Storrs 06269, USA
| | | |
Collapse
|
21
|
Joki T, Machluf M, Atala A, Zhu J, Seyfried NT, Dunn IF, Abe T, Carroll RS, Black PM. Continuous release of endostatin from microencapsulated engineered cells for tumor therapy. Nat Biotechnol 2001; 19:35-9. [PMID: 11135549 DOI: 10.1038/83481] [Citation(s) in RCA: 249] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Research studies suggest that tumor-related angiogenesis contributes to the phenotype of malignant gliomas. We assessed the effect of local delivery of the angiogenesis inhibitor endostatin on human glioma cell line (U-87MG) xenografts. Baby hamster kidney (BHK) cells were stably transfected with a human endostatin (hES) expression vector and were encapsulated in alginate-poly L-lysine (PLL) microcapsules for long-term delivery of hES. The release of biologically active endostatin was confirmed using assays of bovine capillary endothelial (BCE) proliferation and of tube formation. Human endostatin released from the microcapsules brought about a 67. 2% inhibition of BCE proliferation. Furthermore, secreted hES was able to inhibit tube formation in KDR/PAE cells (porcine aortic endothelial cells stably transfected with KDR, a tyrosine kinase) treated with conditioned U-87MG medium. A single local injection of encapsulated endostatin-secreting cells in a nude mouse model resulted in a 72.3% reduction in subcutaneous U87 xenografts' weight 21 days post treatment. This inhibition was achieved by only 150.8 ng/ml human endostatin secreted from 2 x 10(5) encapsulated cells. Encapsulated endostatin-secreting cells are effective for the treatment of human glioblastoma xenografts. Continuous local delivery of endostatin may offer an effective therapeutic approach to the treatment of a variety of tumor types.
Collapse
Affiliation(s)
- T Joki
- Brain Tumor Laboratory, Department of Neurosurgery, Department of Surgery, Brigham Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | | | | | |
Collapse
|