Specificity analysis of sera from breast cancer patients vaccinated with MUC1-KLH plus QS-21

The mucin MUC1 is expressed on breast cancers in an underglycosylated form compared to normal tissues and is therefore a potential target for cancer immunotherapy. MUC1 contains multiple tandem repeats of the 20 amino acid (aa) peptide (VTSAPDTRPAPGSTAPPAHG). The APDTRPA epitope is particularly immunogenic since it is recognized by a variety of murine monoclonal antibodies and by some sera and cytotoxic T-cells from unimmunized patients with epithelial cancers. We have prepared a 30 aa peptide (C)VTSAPDTRPAPGSTAPPAHGVTSAPDTRPA with cysteine at the N-terminal end, and used the cysteine for chemical conjugation to keyhole limpet haemocyanin (KLH). Six breast cancer patients immunized with this conjugate plus the immunological adjuvant QS-21 have all produced high titre (by ELISA) IgG and IgM antibodies against the 30 aa MUC1 peptide, but these sera reacted moderately, or not at all, with MUC1-positive tumour cells. To understand this specificity better, we prepared a series of smaller peptides to determine the epitopes recognized by these immune sera in inhibition assays. Only peptides containing APDTRPA at the C-terminal end were able to completely inhibit ELISA reactivity for the full 30 aa peptide. No sera were completely inhibited by APDTR, APDTRP, PDTRPA or any other peptides that did not contain the full APDTRPA epitope. Remarkably, sera from all six patients recognized this same epitope and were completely inhibited by only this epitope. The specificity of these sera (1) primarily for C-terminal APDTRPA, and the absence of this epitope at the C-terminal end of any tumour mucins, and (2) the N-terminal APDTRPA alanine, which is normally buried in the β turn MUC1 assumes in its secondary structure may explain the moderate to weak reactivity of these high titer sera against MUC1-positive tumour cells. © 1999 Cancer Research Campaig

Emergence of 3D Printed Dosage Forms: Opportunities and Challenges

The recent introduction of the first FDA approved 3D-printed drug has fuelled interest in 3D printing technology, which is set to revolutionize healthcare. Since its initial use, this rapid prototyping (RP) technology has evolved to such as extent that it is currently being used in a wide range of applications including in tissue engineering, dentistry, construction, automotive and aerospace. However, in the pharmaceutical industry this technology is still in its infancy and its potential yet to be fully explored. This paper presents various 3D printing technologies such as stereolithographic, powder based, selective laser sintering, fused deposition modelling and semi-solid extrusion 3D printing. It also provides a comprehensive review of previous attempts at using 3D printing technologies on the manufacturing dosage forms with a particular focus on oral tablets. Their advantages particularly with adaptability in the pharmaceutical field have been highlighted, including design flexibility and control and manufacture which enables the preparation of dosage forms with complex designs and geometries, multiple actives and tailored release profiles. An insight into the technical challenges facing the different 3D printing technologies such as the formulation and processing parameters is provided. Light is also shed on the different regulatory challenges that need to be overcome for 3D printing to fulfil its real potential in the pharmaceutical industry

PPF/DEF-HA composite scaffold using microstereolithography

X111sciescopu

DEVELOPMENT OF 3D PPF/DEF SCAFFOLDS USING MICRO-STEREOLITHOGRAPHY AND SURFACE MODIFICATION

Poly(propylene fumarate) (PPF) is an ultraviolet-curable and biodegradable polymer with potential applications for bone regeneration. In this study, we designed and fabricated three-dimensional (3D) porous scaffolds based on a PPF polymer network using micro-stereolithography (MSTL). The 3D scaffold was well fabricated with a highly interconnected porous structure and porosity of 65%. These results provide a new scaffold fabrication method for tissue engineering. Surface modification is a commonly used and effective method for improving the surface characteristics of biomaterials without altering their bulk properties that avoids the expense and long time associated with the development of new biomaterials. Therefore, we examined surface modification of 3D scaffolds by applying accelerated biomimetic apatite and arginine-glycine-aspartic acid (RGD) peptide coating to promote cell behavior. The apatite coating uniformly covered the scaffold surface after immersion for 24 h in 5-fold simulated body fluid (5SBF) and then the RGD peptide was applied. Finally, the coated 3D scaffolds were seeded with MC3T3-E1 pre-osteoblasts and their biologic properties were evaluated using an MTS assay and histologic staining. We found that 3D PPF/diethyl fumarate (DEF) scaffolds fabricated with MSTL and biomimetic apatite coating can be potentially used in bone tissue engineering.X1169sciescopu

3D scaffold fabrication with PPF/DEF using micro-stereolithography

Current studies on scaffold fabrication have focused on overcoming the limitations imposed by the mechanical properties of existing biodegradable materials and the irregular structures they produce. Recently, several promising biodegradable materials were introduced, including poly(propylene fumarate) (PPF). In addition, the development of micro-stereolithography allows the fabrication of free-form 3D microstructures by dividing a desired shape into several slices of a given thickness. This technology, however, requires a low-viscosity resin to fabricate fine structures, which excludes the use of PPF. To fabricate precise 3D scaffolds using micro-stereolithography, we created a system in which the viscosity of PPF was reduced by adding diethyl fumarate. The fabricated scaffold was sterilized, and fibroblasts in cell culture medium were seeded onto the structure. Cells were fixed and freeze-dried after 4, 7, and 28 days of culture. Under scanning electron microscopy, we observed that the cells were able to attach to the scaffold surface and grow. (c) 2007 Elsevier B.V. All rights reserved.1138sciescopu

3D scaffold fabrication with PPF/DEF using micro-stereolithography

Current studies on scaffold fabrication have focused on overcoming the limitations imposed by the mechanical properties of existing biodegradable materials and the irregular structures they produce. Recently, several promising biodegradable materials were introduced, including poly(propylene fumarate) (PPF). In addition, the development of micro-stereolithography allows the fabrication of free-form 3D microstructures by dividing a desired shape into several slices of a given thickness. This technology, however, requires a low-viscosity resin to fabricate fine structures, which excludes the use of PPF. To fabricate precise 3D scaffolds using micro-stereolithography, we created a system in which the viscosity of PPF was reduced by adding diethyl fumarate. The fabricated scaffold was sterilized, and fibroblasts in cell culture medium were seeded onto the structure. Cells were fixed and freeze-dried after 4, 7, and 28 days of culture. Under scanning electron microscopy, we observed that the cells were able to attach to the scaffold surface and grow. (c) 2007 Elsevier B.V. All rights reserved.

Fabrication and characteristic analysis of a poly(propylene fumarate) scaffold using micro-stereolithography technology

Scaffold fabrication for regenerating functional human tissues has an important role in tissue engineering, and there has been much progress in research on scaffold fabrication. However, current methods are limited by the mechanical properties of existing biodegradable materials and the irregular structures that they produce. Recently, several promising biodegradable materials have been introduced, including poly(propylene fumarate) (PPF). The development of micro-stereolithography allows the fabrication of free-form 3D microstructures as designed. Since this technology requires a low-viscosity resin to fabricate fine structures, we reduced the viscosity of PPF by adding diethyl fumarate. Using our system, the curing characteristics and material properties of the resin were analyzed experimentally. Then, we fabricated waffle shape and 3D scaffolds containing several hundred regular micro pores. This method controlled the pore size, porosity, interconnectivity, and pore distribution. The results show that micro-stereolithography has big advantages over conventional fabrication methods. In addition, the ultimate strength and elastic modulus of the fabricated scaffolds were measured, and cell adhesion to the fabricated scaffold was observed by growing seeded cells on it. These results showed that the PPF/DEF scaffold is a potential bone scaffold for tissue engineering. (c) 2008 Wiley Pefiodicals, Inc.X115841sciescopu