Immunomodulatory Strategies for Cartilage Regeneration in Osteoarthritis

Osteoarthritis (OA) is the most prevalent musculoskeletal disorder and a leading cause of disability globally. Although many efforts have been made to treat this condition, current tissue engineering (TE) and regenerative medicine strategies fail to address the inflammatory tissue environment that leads to the rapid progression of the disease and prevents cartilage tissue formation. First, this review addresses in detail the current anti-inflammatory therapies for OA with a special emphasis on pharmacological approaches, gene therapy, and mesenchymal stromal cell (MSC) intra-articular administration, and discusses the reasons behind the limited clinical success of these approaches at enabling cartilage regeneration. Then, we analyze the state-of-the-art TE strategies and how they can be improved by incorporating immunomodulatory capabilities such as the optimization of biomaterial composition, porosity and geometry, and the loading of anti-inflammatory molecules within an engineered structure. Finally, the review discusses the future directions for the new generation of TE strategies for OA treatment, specifically focusing on the spatiotemporal modulation of anti-inflammatory agent presentation to allow for tailored patient-specific therapies. Impact statement Osteoarthritis (OA) is a prevalent and debilitating musculoskeletal disorder affecting millions worldwide. Despite significant advancements in regenerative medicine and tissue engineering (TE), mitigating inflammation while simultaneously promoting cartilage tissue regeneration in OA remains elusive. In this review article, we discuss current anti-inflammatory therapies and explore their potential synergy with cutting-edge cartilage TE strategies, with a special focus on novel spatiotemporal and patient-specific anti-inflammatory strategies.

Supramolecular Hydrolase Mimics in Equilibrium and Kinetically Trapped States

The folding of proteins into intricate three-dimensional structures to achieve biological functions, such as catalysis, is governed by both kinetic and thermodynamic controls. The quest to design artificial enzymes using minimalist peptides seeks to emulate supramolecular structures existing in a catalytically active state. Drawing inspiration from the nuanced process of protein folding, our study explores the enzyme-like activity of amphiphilic peptide nanosystems in both equilibrium and non-equilibrium states, featuring the formation of supramolecular nanofibrils and nanosheets. In contrast to thermodynamically stable nanosheets, the kinetically trapped nanofibrils exhibit dynamic characteristics (e.g., rapid molecular exchange and relatively weak intermolecular packing), resulting in a higher hydrolase-mimicking activity. We emphasize that a supramolecular microenvironment characterized by an optimal local polarity, microviscosity, and β-sheet hydrogen bonding is conducive to both substrate binding and ester bond hydrolysis. Our work underscores the pivotal role of both thermodynamic and kinetic control in impacting biomimetic catalysis and sheds a light on the development of artificial enzymes.

Characterizing properties of scaffolds 3D printed with peptide-polymer conjugates

Three-dimensional (3D) printing is a popular biomaterials fabrication technique because it enables scaffold composition and architecture to be tuned for different applications. Modifying these properties can also alter mechanical properties, making it challenging to decouple biochemical and physical properties. In this study, inks containing peptide-poly(caprolactone) (PCL) conjugates were solvent-cast 3D printed to create peptide-functionalized scaffolds. We characterized how different concentrations of hyaluronic acid-binding (HAbind-PCL) or mineralizing (E3-PCL) conjugates influenced properties of the resulting 3D-printed constructs. The peptide sequences CGGGRYPISRPRKR (HAbind-PCL; positively charged) and CGGGAAAEEE (E3-PCL; negatively charged) enabled us to evaluate how conjugate chemistry, charge, and concentration affected 3D-printed architecture, conjugate location, and mechanical properties. For both HAbind-PCL and E3-PCL, conjugate addition did not affect ink viscosity, filament diameter, scaffold architecture, or scaffold compressive modulus. Increasing conjugate concentration in the ink prior to printing correlated with an increase in peptide concentration on the scaffold surface. Interestingly, conjugate type affected final conjugate location within the 3D-printed filament cross-section. HAbind-PCL conjugates remained within the filament bulk while E3-PCL conjugates were located closer to the filament surface. E3-PCL at all concentrations did not affect mechanical properties, but an intermediate HAbind-PCL concentration resulted in a moderate decrease in filament tensile modulus. These data suggest final conjugate location within the filament bulk may influence mechanical properties. However, no significant differences were observed between PCL filaments printed without conjugates and filaments printed with higher HAbind-PCL concentrations. These results demonstrate that this 3D printing platform can be used to functionalize the surface without significant changes to the physical properties of the scaffold. The downstream potential of this strategy will enable decoupling of biochemical and physical properties to fine-tune cellular responses and support functional tissue regeneration.

Spatial organization of biochemical cues in 3D-printed scaffolds to guide osteochondral tissue engineering

Functional repair of osteochondral (OC) tissue remains challenging because the transition from bone to cartilage presents gradients in biochemical and physical properties necessary for joint function. Osteochondral regeneration requires strategies that restore the spatial composition and organization found in the native tissue. Several biomaterial approaches have been developed to guide chondrogenic and osteogenic differentiation of human mesenchymal stem cells (hMSCs). These strategies can be combined with 3D printing, which has emerged as a useful tool to produce tunable, continuous scaffolds functionalized with bioactive cues. However, functionalization often includes one or more post-fabrication processing steps, which can lead to unwanted side effects and often produce biomaterials with homogeneously distributed chemistries. To address these challenges, surface functionalization can be achieved in a single step by solvent-cast 3D printing peptide-functionalized polymers. Peptide-poly(caprolactone) (PCL) conjugates were synthesized bearing hyaluronic acid (HA)-binding (HAbind-PCL) or mineralizing (E3-PCL) peptides, which have been shown to promote hMSC chondrogenesis or osteogenesis, respectively. This 3D printing strategy enables unprecedented control of surface peptide presentation and spatial organization within a continuous construct. Scaffolds presenting both cartilage-promoting and bone-promoting peptides had a synergistic effect that enhanced hMSC chondrogenic and osteogenic differentiation in the absence of differentiation factors compared to scaffolds without peptides or only one peptide. Furthermore, multi-peptide organization significantly influenced hMSC response. Scaffolds presenting HAbind and E3 peptides in discrete opposing zones promoted hMSC osteogenic behavior. In contrast, presenting both peptides homogeneously throughout the scaffolds drove hMSC differentiation towards a mixed population of articular and hypertrophic chondrocytes. These significant results indicated that hMSC behavior was driven by dual-peptide presentation and organization. The downstream potential of this platform is the ability to fabricate biomaterials with spatially controlled biochemical cues to guide functional tissue regeneration without the need for differentiation factors.

Interlayer bonding strength of 3D printed PEEK specimens

Recent advances in extrusion-based filament 3D printing technology enable the processability of high-performance polymers. Poly(ether ether ketone) (PEEK) is an important group of high-performance polymer that has been widely used in aerospace, automotive, and biomedical applications. The interlayer bonding strength of 3D printed PEEK is crucial for load-bearing applications, yet studies on 3D printed PEEK are sparse due to processing challenges. In this study, the three-point flexural test is used to study the interlayer bonding strength of 3D-printed PEEK specimens with respect to the printing process parameters, including nozzle temperature, print speed, layer height, and wait-time. A design of experiment (DOE) approach is developed to study correlations between printing parameters and the end-use properties, including flexural stress (σf) and strain at break (εf), flexural modulus (Ef), and crystallinity (χ). Our results show that the nozzle temperature, layer height, and wait-time significantly affect the interlayer bonding strength, with nozzle temperature being the most influential parameter to enhance interlayer bonding strength indicated by a significant increase in σf, εf, and χ. Thermal annealing post-printing is shown to increase the degree of χ and Ef, yet its effect on interlayer bonding strength is minimal, indicating that the interlayer bonding strength is primarily determined during the printing process. This study demonstrates the use of a three-point flexural test integrated with a versatile and robust DOE approach to study the interlayer bonding strength of PEEK to reduce product development time while improving mechanical properties.

Strategies to Control or Mimic Growth Factor Activity for Bone, Cartilage, and Osteochondral Tissue Engineering

Growth factors play a critical role in tissue repair and regeneration. However, their clinical success is limited by their low stability, short half-life, and rapid diffusion from the delivery site. Supraphysiological growth factor concentrations are often required to demonstrate efficacy but can lead to adverse reactions, such as inflammatory complications and increased cancer risk. These issues have motivated the development of delivery systems that enable sustained release and controlled presentation of growth factors. This review specifically focuses on bioconjugation strategies to enhance growth factor activity for bone, cartilage, and osteochondral applications. We describe approaches to localize growth factors using noncovalent and covalent methods, bind growth factors via peptides, and mimic growth factor function with mimetic peptide sequences. We also discuss emerging and future directions to control spatiotemporal growth factor delivery to improve functional tissue repair and regeneration.

Fabricating spatially functionalized 3D-printed scaffolds for osteochondral tissue engineering

Three-dimensional (3D) printing of biodegradable polymers has rapidly become a popular approach to create scaffolds for tissue engineering. This technique enables fabrication of complex architectures and layer-by-layer spatial control of multiple components with high resolution. The resulting scaffolds can also present distinct chemical groups or bioactive cues on the surface to guide cell behavior. However, surface functionalization often includes one or more post-fabrication processing steps, which typically produce biomaterials with homogeneously distributed chemistries that fail to mimic the biochemical organization found in native tissues. As an alternative, our laboratory developed a novel method that combines solvent-cast 3D printing with peptide-polymer conjugates to spatially present multiple biochemical cues in a single scaffold without requiring post-fabrication modification. Here, we describe a detailed, stepwise protocol to fabricate peptide-functionalized scaffolds and characterize their physical architecture and biochemical spatial organization. We used these 3D-printed scaffolds to direct human mesenchymal stem cell differentiation and osteochondral tissue formation by controlling the spatial presentation of cartilage-promoting and bone-promoting peptides. This protocol also describes how to seed scaffolds and evaluate matrix deposition driven by peptide organization.

3D printing with peptide-polymer conjugates for single-step fabrication of spatially functionalized scaffolds

Biodegradable polymer-based scaffolds are widely used to provide support during early stages of regeneration and can be functionalized with various chemical groups or bioactive cues to promote desired cellular behavior. However, these scaffolds are often modified post-fabrication, which can lead to undesired changes and homogeneously distributed chemistries that fail to mimic the spatial biochemical organization found in native tissues. To address these challenges, surface functionalization can be achieved by 3D printing with pre-functionalized biodegradable polymers, such as peptide-modified polymer conjugates, to control the deposition of preferred chemistries. Peptide-PCL conjugates were synthesized with the canonical cell adhesion peptide motif RGDS or its negative control RGES and 3D printed into scaffolds displaying one or both peptides. The peptides were also modified with bioorthogonal groups, biotin and azide, to visualize peptide concentration and location by labeling with complementary fluorophores. Peptide concentration on the scaffold surface increased with increasing peptide-PCL conjugate concentration added to the ink prior to 3D printing, and scaffolds printed with the highest RGDS(biotin)-PCL concentrations showed a significant increase in NIH3T3 fibroblast adhesion. To demonstrate spatial control of peptide functionalization, multiple printer heads were used to print both peptide-PCL conjugates into the same construct in alternating patterns. Cells preferentially attached and spread on RGDS(biotin)-PCL fibers compared to RGES(azide)-PCL fibers, illustrating how spatial functionalization can be used to influence local cell behavior within a single biomaterial. This presents a versatile platform to generate multifunctional biomaterials that can mimic the biochemical organization found in native tissues to support functional regeneration.

Electrospinning Functionalized Polymers for Use as Tissue Engineering Scaffolds

Electrospinning polymers is a versatile technique to generate fibrous, three-dimensional scaffolds for tissue engineering applications. Modifying polymers with functional groups prior to electrospinning offers the opportunity to control the spatial presentation of functional groups within the scaffold as well as incorporate multiple bioactive cues. This chapter describes methods to modify poly(ε-caprolactone) (PCL) with peptides and electrospin these peptide-PCL conjugates to functionalize a scaffold surface in a single step. Methods to adapt standard electrospinning setups to create single- or dual-peptide gradients within a single construct are also described.

Peptide-Functionalized Fluorescent Particles for In Situ Detection of Nitric Oxide via Peroxynitrite-Mediated Nitration

Nitric oxide (NO) is a free radical signaling molecule that plays a crucial role in modulating physiological homeostasis across multiple biological systems. NO dysregulation is linked to the pathogenesis of multiple diseases; therefore, its quantification is important for understanding pathophysiological processes. The detection of NO is challenging, typically limited by its reactive nature and short half-life. Additionally, the presence of interfering analytes and accessibility to biological fluids in the native tissues make the measurement technically challenging and often unreliable. Here, a bio-inspired peptide-based NO sensor is developed, which detects NO-derived oxidants, predominately peroxynitrite-mediated nitration of tyrosine residues. It is demonstrated that these peptide-based NO sensors can detect peroxynitrite-mediated nitration in response to physiological shear stress by endothelial cells in vitro. Using the peptide-conjugated fluorescent particle immunoassay, peroxynitrite-mediated nitration activity with a detection limit of ≈100 × 10-9 m is detected. This study envisions that the NO detection platform can be applied to a multitude of applications including monitoring of NO activity in healthy and diseased tissues, localized detection of NO production of specific cells, and cell-based/therapeutic screening of peroxynitrite levels to monitor pronitroxidative stress in biological samples.

Multimodal Hydrogel-Based Platform To Deliver and Monitor Cardiac Progenitor/Stem Cell Engraftment

Retention and survival of transplanted cells are major limitations to the efficacy of regenerative medicine, with short-term paracrine signals being the principal mechanism underlying current cell therapies for heart repair. Consequently, even improvements in short-term durability may have a potential impact on cardiac cell grafting. We have developed a multimodal hydrogel-based platform comprised of a poly(ethylene glycol) network cross-linked with bioactive peptides functionalized with Gd(III) in order to monitor the localization and retention of the hydrogel in vivo by magnetic resonance imaging. In this study, we have tailored the material for cardiac applications through the inclusion of a heparin-binding peptide (HBP) sequence in the cross-linker design and formulated the gel to display mechanical properties resembling those of cardiac tissue. Luciferase-expressing cardiac stem cells (CSC-Luc2) encapsulated within these gels maintained their metabolic activity for up to 14 days in vitro. Encapsulation in the HBP hydrogels improved CSC-Luc2 retention in the mouse myocardium and hind limbs at 3 days by 6.5- and 12- fold, respectively. Thus, this novel heparin-binding based, Gd(III)-tagged hydrogel and CSC-Luc2 platform system demonstrates a tailored, in vivo detectable theranostic cell delivery system that can be implemented to monitor and assess the transplanted material and cell retention.

Enhanced articular cartilage by human mesenchymal stem cells in enzymatically mediated transiently RGDS-functionalized collagen-mimetic hydrogels

Recapitulation of the articular cartilage microenvironment for regenerative medicine applications faces significant challenges due to the complex and dynamic biochemical and biomechanical nature of native tissue. Towards the goal of biomaterial designs that enable the temporal presentation of bioactive sequences, recombinant bacterial collagens such as Streptococcal collagen-like 2 (Scl2) proteins can be employed to incorporate multiple specific bioactive and biodegradable peptide motifs into a single construct. Here, we first modified the backbone of Scl2 with glycosaminoglycan-binding peptides and cross-linked the modified Scl2 into hydrogels via matrix metalloproteinase 7 (MMP7)-cleavable or non-cleavable scrambled peptides. The cross-linkers were further functionalized with a tethered RGDS peptide creating a system whereby the release from an MMP7-cleavable hydrogel could be compared to a system where release is not possible. The release of the RGDS peptide from the degradable hydrogels led to significantly enhanced expression of collagen type II (3.9-fold increase), aggrecan (7.6-fold increase), and SOX9 (5.2-fold increase) by human mesenchymal stem cells (hMSCs) undergoing chondrogenesis, as well as greater extracellular matrix accumulation compared to non-degradable hydrogels (collagen type II; 3.2-fold increase, aggrecan; 4-fold increase, SOX9; 2.8-fold increase). Hydrogels containing a low concentration of the RGDS peptide displayed significantly decreased collagen type I and X gene expression profiles, suggesting a major advantage over either hydrogels functionalized with a higher RGDS peptide concentration, or non-degradable hydrogels, in promoting an articular cartilage phenotype. These highly versatile Scl2 hydrogels can be further manipulated to improve specific elements of the chondrogenic response by hMSCs, through the introduction of additional bioactive and/or biodegradable motifs. As such, these hydrogels have the possibility to be used for other applications in tissue engineering.

Statement of Significance

Recapitulating aspects of the native tissue biochemical microenvironment faces significant challenges in regenerative medicine and tissue engineering due to the complex and dynamic nature of the tissue. The ability to take advantage of, mimic, and modulate cell-mediated processes within novel naturally-derived hydrogels is of great interest in the field of biomaterials to generate constructs that more closely resemble the biochemical microenvironment and functions of native biological tissues such as articular cartilage. Towards this goal, the temporal presentation of bioactive sequences such as RGDS on the chondrogenic differentiation of human mesenchymal stem cells is considered important as it has been shown to influence the chondrogenic phenotype. Here, a novel and versatile platform to recreate a high degree of biological complexity is proposed, which could also be applicable to other tissue engineering and regenerative medicine applications.

Plasmonic Chirality Imprinting on Nucleobase-Displaying Supramolecular Nanohelices by Metal-Nucleobase Recognition

Supramolecular self-assembly is an important process that enables the conception of complex structures mimicking biological motifs. Herein, we constructed helical fibrils through chiral self-assembly of nucleobase-peptide conjugates (NPCs), where achiral nucleobases are helically displayed on the surface of fibrils, comparable to polymerized nucleic acids. Selective binding between DNA and the NPC fibrils was observed with fluorescence polarization. Taking advantage of metal-nucleobase recognition, we highlight the possibility of deposition/assembly of plasmonic nanoparticles onto the fibrillar constructs. In this approach, the supramolecular chirality of NPCs can be adaptively imparted to metallic nanoparticles, covering them to generate structures with plasmonic chirality that exhibit significantly improved colloidal stability. The self-assembly of rationally designed NPCs into nanohelices is a promising way to engineer complex, optically diverse nucleobase-derived nanomaterials.

Controlled Sub-Nanometer Epitope Spacing in a Three-Dimensional Self-Assembled Peptide Hydrogel

Cells in the body use a variety of mechanisms to ensure the specificity and efficacy of signal transduction. One way that this is achieved is through tight spatial control over the position of different proteins, signaling sequences, and biomolecules within and around cells. For instance, the extracellular matrix protein fibronectin presents RGDS and PHSRN sequences that synergistically bind the α₅β₁ integrin when separated by 3.2 nm but are unable to bind when this distance is >5.5 nm.1 Building biomaterials to controllably space different epitopes with subnanometer accuracy in a three-dimensional (3D) hydrogel is challenging. Here, we synthesized peptides that self-assemble into nanofiber hydrogels utilizing the β-sheet motif, which has a known regular spacing along the peptide backbone. By modifying specific locations along the peptide, we are able to controllably space different epitopes with subnanometer accuracy at distances from 0.7 nm to over 6 nm, which is within the size range of many protein clusters. Endothelial cells encapsulated within hydrogels displaying RGDS and PHSRN in the native 3.2 nm spacing showed a significant upregulation in the expression of the alpha 5 integrin subunit compared to those in hydrogels with a 6.2 nm spacing, demonstrating the physiological relevance of the spacing. Furthermore, after 24 h the cells in hydrogels with the 3.2 nm spacing appeared to be more spread with increased staining for the α₅β₁ integrin. This self-assembling peptide system can controllably space multiple epitopes with subnanometer accuracy, demonstrating an exciting platform to study the effects of ligand density and location on cells within a synthetic 3D environment.

Pericyte Seeded Dual Peptide Scaffold with Improved Endothelialization for Vascular Graft Tissue Engineering

The development of synthetic vascular grafts for coronary artery bypass is challenged by insufficient endothelialization, which increases the risk of thrombosis, and the lack of native cellular constituents, which favors pathological remodeling. Here, a bifunctional electrospun poly(ε-caprolactone) (PCL) scaffold with potential for synthetic vascular graft applications is presented. This scaffold incorporates two tethered peptides: the osteopontin-derived peptide (Adh) on the "luminal" side and a heparin-binding peptide (Hep) on the "abluminal" side. Additionally, the "abluminal" side of the scaffold is seeded with saphenous vein-derived pericytes (SVPs) as a source of proangiogenic growth factors. The Adh peptide significantly increases endothelial cell adhesion, while the Hep peptide promotes accumulation of vascular endothelial growth factor secreted by SVPs. SVPs increase endothelial migration both in a transwell assay and a modified scratch assay performed on the PCL scaffold. Seeding of SVPs on the "abluminal"/Hep side of the scaffold further increases endothelial cell density, indicating a combinatory effect of the peptides and pericytes. Finally, SVP-seeded scaffolds are preserved by freezing in a xeno-free medium, maintaining good cell viability and function. In conclusion, this engineered scaffold combines patient-derived pericytes and spatially organized functionalities, which synergistically increase endothelial cell density and growth factor retention.

Temporally degradable collagen-mimetic hydrogels tuned to chondrogenesis of human mesenchymal stem cells

Tissue engineering strategies for repairing and regenerating articular cartilage face critical challenges to recapitulate the dynamic and complex biochemical microenvironment of native tissues. One approach to mimic the biochemical complexity of articular cartilage is through the use of recombinant bacterial collagens as they provide a well-defined biological 'blank template' that can be modified to incorporate bioactive and biodegradable peptide sequences within a precisely defined three-dimensional system. We customized the backbone of a Streptococcal collagen-like 2 (Scl2) protein with heparin-binding, integrin-binding, and hyaluronic acid-binding peptide sequences previously shown to modulate chondrogenesis and then cross-linked the recombinant Scl2 protein with a combination of matrix metalloproteinase 7 (MMP7)- and aggrecanase (ADAMTS4)-cleavable peptides at varying ratios to form biodegradable hydrogels with degradation characteristics matching the temporal expression pattern of these enzymes in human mesenchymal stem cells (hMSCs) during chondrogenesis. hMSCs encapsulated within the hydrogels cross-linked with both degradable peptides exhibited enhanced chondrogenic characteristics as demonstrated by gene expression and extracellular matrix deposition compared to the hydrogels cross-linked with a single peptide. Additionally, these combined peptide hydrogels displayed increased MMP7 and ADAMTS4 activities and yet increased compression moduli after 6 weeks, suggesting a positive correlation between the degradation of the hydrogels and the accumulation of matrix by hMSCs undergoing chondrogenesis. Our results suggest that including dual degradation motifs designed to respond to enzymatic activity of hMSCs going through chondrogenic differentiation led to improvements in chondrogenesis. Our hydrogel system demonstrates a bimodal enzymatically degradable biological platform that can mimic native cellular processes in a temporal manner. As such, this novel collagen-mimetic protein, cross-linked via multiple enzymatically degradable peptides, provides a highly adaptable and well defined platform to recapitulate a high degree of biological complexity, which could be applicable to numerous tissue engineering and regenerative medicine applications.

Harnessing the Versatility of Bacterial Collagen to Improve the Chondrogenic Potential of Porous Collagen Scaffolds

Collagen I foams are used in the clinic as scaffolds to promote articular cartilage repair as they provide a bioactive environment for cells with chondrogenic potential. However, collagen I as a base material does not allow for precise control over bioactivity. Alternatively, recombinant bacterial collagens can be used as "blank slate" collagen molecules to offer a versatile platform for incorporation of selected bioactive sequences and fabrication into 3D scaffolds. Here, we show the potential of Streptococcal collagen-like 2 (Scl2) protein foams modified with peptides designed to specifically and noncovalently bind hyaluronic acid and chondroitin sulfate to improve chondrogenesis of human mesenchymal stem cells (hMSCs) compared to collagen I foams. Specific compositions of functionalized Scl2 foams lead to improved chondrogenesis compared to both nonfunctionalized Scl2 and collagen I foams, as indicated by gene expression, extracellular matrix accumulation, and compression moduli. hMSCs cultured in functionalized Scl2 foams exhibit decreased collagens I and X gene and protein expression, suggesting an advantage over collagen I foams in promoting a chondrocytic phenotype. These highly modular foams can be further modified to improve specific aspects chondrogenesis. As such, these scaffolds also have the potential to be tailored for other regenerative medicine applications.

Creating biomaterials with spatially organized functionality

Biomaterials for tissue engineering provide scaffolds to support cells and guide tissue regeneration. Despite significant advances in biomaterials design and fabrication techniques, engineered tissue constructs remain functionally inferior to native tissues. This is largely due to the inability to recreate the complex and dynamic hierarchical organization of the extracellular matrix components, which is intimately linked to a tissue's biological function. This review discusses current state-of-the-art strategies to control the spatial presentation of physical and biochemical cues within a biomaterial to recapitulate native tissue organization and function.

Mapping Local Cytosolic Enzymatic Activity in Human Esophageal Mucosa with Porous Silicon Nanoneedles

Porous silicon nanoneedles can map Cathepsin B activity across normal and tumor human esophageal mucosa. Assembling a peptide-based Cathepsin B cleavable sensor over a large array of nano-needles allows the discrimination of cancer cells from healthy ones in mixed culture. The same sensor applied to tissue can map Cathepsin B activity with high resolution across the tumor margin area of esophageal adenocarcinoma.

Modular and Versatile Spatial Functionalization of Tissue Engineering Scaffolds through Fiber-Initiated Controlled Radical Polymerization

Native tissues are typically heterogeneous and hierarchically organized, and generating scaffolds that can mimic these properties is critical for tissue engineering applications. By uniquely combining controlled radical polymerization (CRP), end-functionalization of polymers, and advanced electrospinning techniques, a modular and versatile approach is introduced to generate scaffolds with spatially organized functionality. Poly-ε-caprolactone is end functionalized with either a polymerization-initiating group or a cell-binding peptide motif cyclic Arg-Gly-Asp-Ser (cRGDS), and are each sequentially electrospun to produce zonally discrete bilayers within a continuous fiber scaffold. The polymerization-initiating group is then used to graft an antifouling polymer bottlebrush based on poly(ethylene glycol) from the fiber surface using CRP exclusively within one bilayer of the scaffold. The ability to include additional multifunctionality during CRP is showcased by integrating a biotinylated monomer unit into the polymerization step allowing postmodification of the scaffold with streptavidin-coupled moieties. These combined processing techniques result in an effective bilayered and dual-functionality scaffold with a cell-adhesive surface and an opposing antifouling non-cell-adhesive surface in zonally specific regions across the thickness of the scaffold, demonstrated through fluorescent labelling and cell adhesion studies. This modular and versatile approach combines strategies to produce scaffolds with tailorable properties for many applications in tissue engineering and regenerative medicine.

Self-assembly of collagen building blocks guided by electric fields

Show me the way: protein building blocks are programmed to assemble hierarchically and yield a defined fiber morphology of micrometric length and precise nanometric diameter. The key step of this method is to align the building blocks with an AC field prior to assembly. The resulting protein nanofibers are straightforwardly integrated with the circuitry for potential applications in bionanotechnology.

Peptide-directed spatial organization of biomolecules in dynamic gradient scaffolds

Specific binding peptides are used to spatially organize biomolecule gradients within an electrospun fiber scaffold. Different biomolecule-binding peptide-polymer conjugates are sequentially co-electrospun with a fiber-forming host polymer to generate opposing gradients of peptide functionalization. The binding peptides specifically and non-covalently guide the spatial arrangement of biomolecules into dynamic gradients within the scaffold, mimicking biological gradients found in native tissues.

The promotion of functional urinary bladder regeneration using anti-inflammatory nanofibers

Current attempts at tissue regeneration utilizing synthetic and decellularized biologic-based materials have typically been met in part by innate immune responses in the form of a robust inflammatory reaction at the site of implantation or grafting. This can ultimately lead to tissue fibrosis with direct negative impact on tissue growth, development, and function. In order to temper the innate inflammatory response, anti-inflammatory signals were incorporated through display on self-assembling peptide nanofibers to promote tissue healing and subsequent graft compliance throughout the regenerative process. Utilizing an established urinary bladder augmentation model, the highly pro-inflammatory biologic scaffold (decellularized small intestinal submucosa) was treated with anti-inflammatory peptide amphiphiles (AIF-PAs) or control peptide amphiphiles and used for augmentation. Significant regenerative advantages of the AIF-PAs were observed including potent angiogenic responses, limited tissue collagen accumulation, and the modulation of macrophage and neutrophil responses in regenerated bladder tissue. Upon further characterization, a reduction in the levels of M2 macrophages was observed, but not in M1 macrophages in control groups, while treatment groups exhibited decreased levels of M1 macrophages and stabilized levels of M2 macrophages. Pro-inflammatory cytokine production was decreased while anti-inflammatory cytokines were up-regulated in treatment groups. This resulted in far fewer incidences of tissue granuloma and bladder stone formation. Finally, functional urinary bladder testing revealed greater bladder compliance and similar capacities in groups treated with AIF-PAs. Data demonstrate that AIF-PAs can alleviate galvanic innate immune responses and provide a highly conducive regenerative milieu that may be applicable in a variety of clinical settings.

Electrostatic control of structure in self-assembled membranes

Self-assembling peptide amphiphiles (PAs) can form hierarchically ordered membranes when brought in contact with aqueous polyelectrolytes of the opposite charge by rapidly creating a diffusion barrier composed of filamentous nanostructures parallel to the plane of the incipient membrane. Following this event, osmotic forces and charge complexation template nanofiber growth perpendicular to the plane of the membrane in a dynamic self-assembly process. In this work, we show that this hierarchical structure requires massive interfacial aggregation of PA molecules, suggesting the importance of rapid diffusion barrier formation. Strong PA aggregation is induced here through the use of heparin-binding PAs with heparin and also with polyelectrolytes of varying charge density. Small angle X-ray scattering shows that in the case of weak PA-polyelectrolyte interaction, membranes formed display a cubic phase ordering on the nanoscale that likely results from clusters of PA nanostructures surrounded by polyelectrolyte chains.

A designer peptide as a template for growing Au nanoclusters

A peptide was designed to generate a sub-nanometric template that guides the growth of fluorescent gold nanoclusters.

LMTK3 is implicated in endocrine resistance via multiple signaling pathways

Resistance to endocrine therapy in breast cancer is common. With the aim of discovering new molecular targets for breast cancer therapy, we have recently identified LMTK3 as a regulator of the estrogen receptor-alpha (ERα) and wished to understand its role in endocrine resistance. We find that inhibition of LMTK3 in a xenograft tamoxifen (Tam)-resistant (BT474) breast cancer mouse model results in re-sensitization to Tam as demonstrated by a reduction in tumor volume. A whole genome microarray analysis, using a BT474 cell line, reveals genes significantly modulated (positively or negatively) after LMTK3 silencing, including some that are known to be implicated in Tam resistance, notably c-MYC, HSPB8 and SIAH2. We show that LMTK3 is able to increase the levels of HSPB8 at a transcriptional and translational level thereby protecting MCF7 cells from Tam-induced cell death, by reducing autophagy. Finally, high LMTK3 levels at baseline in tumors are predictive for endocrine resistance; therapy does not lead to alteration in levels, whereas in patient's plasma samples, acquired LMTK3 gene amplification (copy number variation) was associated with relapse while receiving Tam. In aggregate, these data support a role for LMTK3 in both innate (intrinsic) and acquired (adaptive) endocrine resistance in breast cancer.

A bioactive self-assembled membrane to promote angiogenesis

We report here on a bioactive hierarchically structured membrane formed by self-assembly. The membrane is formed with hyaluronic acid and peptide amphiphiles with binding affinity for heparin, and its hierarchical structure contains both an amorphous zone and a layer of fibrils oriented perpendicular to the membrane plane. The design of bioactivity is based on the potential ability to bind and slowly release heparin-binding growth factors. Human mesenchymal stem cells (hMSCs) seeded on these membranes attached and remained viable. Basic fibroblast growth factor (FGF2) and vascular endothelial growth factor (VEGF) were incorporated within the membrane structure prior to self-assembly and released into media over a prolonged period of time (14 days). Using the chicken chorioallantoic membrane (CAM) assay, we also found that these membranes induced a significant and rapid enhancement of angiogenesis relative to controls.

Self-assembling nanostructures to deliver angiogenic factors to pancreatic islets

Supramolecular self-assembly of nanoscale filaments offers a vehicle to signal cells within dense cell aggregates such as pancreatic islets. We previously developed a heparin-binding peptide amphiphile (HBPA) that self-assembles into nanofiber gels at concentrations of 1% by weight when mixed with heparin and activates heparin-binding, angiogenic growth factors. We report here on the use of these molecules at concentrations 100 times lower to drive delivery of the nanofibers into the dense islet interior. Using fluorescent markers, HBPA molecules, heparin, and FGF2 were shown to be present in and on the surface of murine islets. The intraislet nanofibers were found to be necessary to retain FGF2 within the islet for 48 h and to increase cell viability significantly for at least 7 days in culture. Furthermore, enhanced insulin secretion was observed with the nanofibers for 3 days in culture. Delivery of FGF2 and VEGF in conjunction with the HBPA/heparin nanofibers also induced a significant amount of islet endothelial cell sprouting from the islets into a peptide amphiphile 3-D matrix. We believe the infiltration of bioactive nanofibers in the interior of islets as an artificial ECM can improve cell viability and function in vitro and enhance their vascularization in the presence of growth factors such as FGF2 and VEGF. The approach described here may have significant impact on islet transplantation to treat type 1 diabetes.

Nitric oxide and nanotechnology: a novel approach to inhibit neointimal hyperplasia

OBJECTIVE

Nitric oxide (NO) has been shown to inhibit neointimal hyperplasia after arterial interventions in several animal models. To date, however, NO-based therapies have not been used in the clinical arena. Our objective was to combine nanofiber delivery vehicles with NO chemistry to create a novel, more potent NO-releasing therapy that can be used clinically. Thus, the aim of this study was to evaluate the perivascular application of spontaneously self-assembling NO-releasing nanofiber gels. Our hypothesis was that this application would prevent neointimal hyperplasia.

METHODS

Gels consisted of a peptide amphiphile, heparin, and a diazeniumdiolate NO donor (1-[N-(3-Aminopropyl)-N-(3-ammoniopropyl)]diazen-1-ium-1,2-diolate [DPTA/NO] or disodium 1-[(2-Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate [PROLI/NO]). Nitric oxide release from the gels was evaluated by the Griess reaction, and scanning electron microscopy confirmed nanofiber formation. Vascular smooth muscle cell (VSMC) proliferation and cell death were assessed in vitro by (3)H-thymidine incorporation and Personal Cell Analysis (PCA) system (Guava Technologies, Hayward, Calif). For the in vivo work, gels were modified by reducing the free-water content. Neointimal hyperplasia after periadventitial gel application was evaluated using the rat carotid artery injury model at 14 days (n = 6 per group). Inflammation and proliferation were examined in vivo with immunofluorescent staining against CD45, ED1, and Ki67 at 3 days (n = 2 per group), and graded by blinded observers. Endothelialization was assessed by Evans blue injection at 7 days (n = 3 per group).

RESULTS

Both DPTA/NO and PROLI/NO, combined with the peptide amphiphile and heparin, formed nanofiber gels and released NO for 4 days. In vitro, DPTA/NO inhibited VSMC proliferation and induced cell death to a greater extent than PROLI/NO. However, the DPTA/NO nanofiber gel only reduced neointimal hyperplasia by 45% (intima/media [I/M] area ratio, 0.45 +/- 0.07), whereas the PROLI/NO nanofiber gel reduced neointimal hyperplasia by 77% (I/M area ratio, 0.19 +/- 0.03, P < .05) vs control (injury alone I/M area ratio, 0.83 +/- 0.07; P < .05). Both DPTA/NO and PROLI/NO nanofiber gels significantly inhibited proliferation in vivo (1.06 +/- 0.30 and 0.19 +/- 0.11 vs injury alone, 2.02 +/- 0.20, P < .05), yet had minimal effect on apoptosis. Only the PROLI/NO nanofiber gel inhibited inflammation (monocytes and leukocytes). Both NO-releasing nanofiber gels stimulated re-endothelialization.

CONCLUSIONS

Perivascular application of NO-releasing self-assembling nanofiber gels is an effective and simple therapy to prevent neointimal hyperplasia after arterial injury. Our study demonstrates that the PROLI/NO nanofiber gel most effectively prevented neointimal hyperplasia and resulted in less inflammation than the DPTA/NO nanofiber gel. This therapy has great clinical potential to prevent neointimal hyperplasia after open vascular interventions in patients.

Effects of a herbal compound containing bupleurum on human lymphocytes

Bupleurum-containing compounds, such as KY88 Liver Livo are thought to have immunomodulatory effects. This study investigated the effects of KY88 Liver Livo on the mitogenic induction of lymphocytes in vitro. Fifteen healthy human adult volunteers, aged between 20 and 50 years, provided peripheral blood samples from which lymphocytes were obtained by Ficoll-Hypaque centrifugation. The separated lymphocytes were stimulated by phytohaemagglutinin and KY88 Liver Livo in varying concentrations for 72 hours, with greater cluster and colony formation evident compared with lymphocytes in a control preparation. KY88 Liver Livo was also found to induce the secretion of granulocyte-macrophage colony-stimulating factor in a dose-dependent fashion. These preliminary in vitro studies suggest that KY88 Liver Livo may have potential clinical value in the treatment of chronic viral infection and in the management of immunocompromised patients.

Neoadjuvant chemotherapy for Chinese women with locally advanced breast cancer

Locally advanced breast cancer carries a poor prognosis and is still prevalent in developing countries. The current management usually involves administration of neoadjuvant chemotherapy (NCT). From March 1990 through December 1997, 173 Chinese patients with tumor size greater than 4 cm were treated; 38 received NCT and the other 135 postoperative adjuvant chemotherapy. The regimens for NCT were FEC (5-fluorouracil 600 mg/m2, epirubicin 50 mg/m2, and cyclophosphamide 600 mg/m2) for 29 patients and Adriamycin 75 mg/m2 for the rest of the group. Postoperatively the NCT patients received the standard CMF regimen (oral cyclophosphamide 100 mg/m2 for 14 days and intravenous methotrexate 40 mg/m2 and 5-fluorouracil 600 mg/m2 on days one and eight of each cycle). The postoperative adjuvant chemotherapy group received only the CMF regimen. Tumor response after NCT was measured clinically and histologically. The response rate was 75 per cent with 13.2 per cent being complete response. Although there is no difference in response rate the actual reduction in size was greater for patients receiving Adriamycin than FEC (P = 0.001). The only predictive factor of response to NCT was the type of chemotherapy administered. None of the tumor characteristics such as size, nodal status, histological grading, lymphovascular permeation, hormonal receptor status, and c-erb-B2 expression were found to be significant. The overall 5-year probability of survival was 0.44, and there was no difference between groups. The factor important for prognosis was axillary nodal status on histology. The use of NCT did not improve outcome. In summary our results showed that NCT was feasible for Chinese women and good response could be achieved. However, it is the axillary nodal status that determines the final outcome.

The use of focus group interviews in Asian medical education evaluative research

OBJECTIVE

To evaluate the use of focus group interviews in Asian medical education evaluative research.

METHODS

Randomly selected medical students were invited to participate in 30 focus group interviews to provide in-depth data about the effect on their learning of the introduction of early clinical skills. Efforts were made to meet all the students to help them understand the objectives of the focus group. Confidentiality was emphasised and a non-faculty interviewer was recruited for the interviews.

RESULTS

The students considered the use of focus groups to be a more meaningful way of collecting students' opinions than other methods, for example structured questionnaire, because it allowed an interactive discussion. They also felt that having an independent non-faculty interview moderator had encouraged them to express their opinions more candidly during the interviews.

CONCLUSION

The use of focus group interviews among Asian medical students for evaluative research is practical and efficient.

Detection of circulating breast cancer cells with multiple-marker RT-PCR assay

RT-PCR assay for multiple markers has been shown to increase the detection rate of circulating tumor cells. This assay targeted against cytokeratin 19 (CK19), cytokeratin 20 (CK20) and beta-subunit of human chorionic gonadotropin (beta-hCG) was used to detect circulating breast cancer cells. 5 ml of peripheral blood was drawn before any surgical procedures from 72 breast cancer patients and 30 cases with benign breast disease. Total RNA was extracted from peripheral blood mononuclear cells, reverse-transcripted and amplified. For the benign cases, 10% (3/30) were positive for CK19 and all were negative for CK20 and beta-hCG, whereas 9.72% (7/72), 2.78% (2/72) and 12.5% (9/72) of the malignant cases were positive for CK19, CK20 and beta-hCG respectively. The detection rate of circulating breast cancer cells was unchanged when CK19 was combined with CK20, but it increased to 18.1% (13/72) when the marker was combined with beta-hCG. A significant difference was observed for beta-hCG between benign cases and affected patients with stage II, III and IV disease (p = 0.026). In conclusion, positive RT-PCR signals in blood samples of affected patients correlated with stage, in particular for beta-hCG. CK19/beta-hCG was a promising marker combination.

Practice of breast self-examination among high risk Chinese women in Hong Kong

BACKGROUND

The incidence of breast cancer in Hong Kong is increasing and breast self-examination (BSE) as a screening tool is becoming more popular, especially among first-degree relatives (FDR) of breast cancer victims. BSE may be more applicable to Chinese women as their breast size is smaller. This study explores the BSE practice in this group of women.

METHODS

A cross sectional study was conducted by sending questionnaires to 330 FDR of breast cancer patients treated in the Department of Surgery, University of Hong Kong. BSE behavior was studied with respect to its frequency, awareness, completeness and confidence of practice.

RESULTS

110 subjects returned the questionnaires with a response rate of 33%. The mean age of the respondent was 37 years. Only 57 women (52%) were practicers. The practicers have a stronger BSE awareness (P < 0.01) and a lower mean score on thought barriers (P = 0.002) than the non-practicers. 40% of the practicers gain their BSE knowledge through clinicians and their mean period of practice was 3.2 years. 68% of the practicers performed BSE completely. The overall confidence rate was 35%, but the rate was 43% among those who performed complete BSE. Thirteen factors possibly related to the completeness and rate of confidence of BSE examination were studied. The only factor that significantly determined completeness was the time spent for each examination (P = 0.002). The complete practicers required a longer time than the incomplete practicers (6.60 and 2.96 min, respectively). Women with a stronger BSE intention (P = 0.001) and a lower mean score on thought barriers (P = 0.001) performed the examination confidently.

CONCLUSIONS

Slightly over half of the FDR practice BSE. The majority perform a complete BSE but they are not confident in finding abnormalities. Women spending more time on BSE are associated with a higher rate of completeness. However, only those with a stronger BSE intention and lesser thought barriers are more confident in their practice.

Hormonal receptor determination of 1,052 Chinese breast cancers

BACKGROUND AND OBJECTIVES

Hormonal receptors are important prognostic factors for breast cancer. The reported figures in the literature are mostly on Caucasians. This study analyzes the receptor profile of 1,052 Chinese patients.

METHODS

The age of the patients ranged from 20-93 years; 48% were premenopausal and 52% postmenopausal. Estrogen receptor (ER) and progesterone receptor (PgR) were measured quantitatively by enzyme immunoassay (EIA) using the rat monoclonal antibody (ABBOTT ER-EIA). Specimens with values >15 fmol/mg were considered positive according to manufacturer's recommendation.

RESULTS

ER was positive in 53% and 61.6% of the pre- and postmenopausal women respectively (P < 0.0075); PgR was positive in 51.5% and 46.2% respectively (P > 0.05). The mean values of ER were higher for postmenopausal women (P < 0.0001) but the values for PgR were similar between the two groups (P > 0.05). When the values were analyzed with respect to age, there was an increasing trend for ER. No such trend was noted for PgR. Subgroup analysis showed that there were more ER+PgR+ tumors among postmenopausal than among premenopausal women. Tumors with dubious receptor status (ER+PgR- or ER-PgR+) were more prevalent at perimenopausal age.

CONCLUSIONS

Chinese patients have lower receptor values and positivity rates than those reported for Caucasians. Receptor-positive tumors tend to occur in postmenopausal women.

Clarithromycin attenuates mastectomy-induced acute inflammatory response

Based on the observation that administration of clarithromycin led to an attenuation of the inflammatory response induced by surgical trauma in a guinea pig model, we investigated the potential beneficial effects of clarithromycin on the local and systemic inflammatory response in patients undergoing mastectomy in an open-label prospective study. During a 16-month period, 54 patients who underwent mastectomy were randomly divided into two groups. In one group, the patients received oral clarithromycin at a dose of 500 mg twice a day, from the day before to 3 days after mastectomy. There was no significant difference in the incidence of antibiotic prophylaxis-related toxicities or postoperative infections between the patients who received clarithromycin and those who did not. Clarithromycin treatment was significantly associated with an attenuation of febrile response, tachycardia, tachypnea, and an increase in monocyte counts (P, <0.0001, <0.01, <0.05, and <0.01, respectively). Clarithromycin also reduced the intensity and duration of postoperative pain (P, <0.05 and <0.005, respectively) and increased the range of motion of the involved shoulder (P < 0.05 for abduction and flexion). We conclude that clarithromycin effectively modulates the acute inflammatory response associated with mastectomy and produces a better clinical outcome.

Fine needle aspiration may shed breast cells into peripheral blood as determined by RT-PCR

OBJECTIVE

A diagnostic test applying reverse-transcriptase chain reaction (RT-PCR) assay targeted against cytokeratin 19 (CK19), cytokeratin 20 (CK20) and the beta-subunit of human chorionic gonadotropin (beta-hCG) mRNAs was used to evaluate the impact of fine needle aspiration (FNA) on breast cell shedding into peripheral blood.

METHODS

The sensitivity of this assay was based on the different degree of admix of MCF-7 breast cancer cell line with HL-60 leukemic cell line. For blood samples of 24 cases with benign breast diseases and 20 cases with malignant ones, 5 ml of peripheral blood was drawn before and within 10 min after puncture. Total RNA was extracted from peripheral blood mononuclear (PBMN) cells; beta-actin was used to assess the quality of cDNA. RT-PCR products were run in ethidium bromide gel and observed under ultraviolet. RT-PCR products for beta-hCG were digested with Sty I endonuclease to confirm the specificity.

RESULTS

The sensitivity of RT-PCR assay was 1 MCF-7 cell in 10(5) HL-60 cells for CK19 and CK20, and 1 in 10(6) for beta-hCG. For 24 benign cases, none of the pre- FNA samples was positive for CK20 and beta-hCG, and 3 cases (12.5%) were positive for CK19. As for 20 malignant cases, 1 pre-FNA sample was positive for all three markers and 2 other samples were positive for CK19. After aspiration, 3/21 benign cases and 1/17 malignant case with pre-FNA negative signals became positive for CK19, while 3/19 malignant cases with pre-FNA negative signals were converted to a positive result for CK20 and beta-hCG. Of 6 pre-FNA positive cases, all cases remained positive for the respective marker.

CONCLUSION

FNA to breast tumor may cause hematogenous dissemination of breast cells.

Detection of circulating breast cancer cells by reverse transcriptase polymerase chain reaction (RT-PCR)

The confounding problem in treatment of breast cancer is the metastasis of breast tumour. Reverse transcriptase polymerase chain reaction (RT-PCR) has been recently used in the detection of circulating breast cancer cells. This review reports on the development of this assay as well as its advantages and disadvantages. We feel that cytokeratin 20 and beta -human chorionic gonadotropin (hCG) mRNA are the best markers for the detection of circulating breast cancer cells. We suggest that the multiple RNA marker RT-PCR assay can help to increase both sensitivity and specificity of detection, and that quantitative RT-PCR assay is more effective than the qualitative assay in the detection of circulating breast cancer cells.

Comparison of tamoxifen with danazol in the management of idiopathic gynecomastia

Idiopathic gynecomastia, unilateral or bilateral, is a common physical finding in normal men. Successful treatment using tamoxifen (antiestrogen) and danazol (antiandrogen) has recently been reported. We compared the efficacy of tamoxifen and danazol in the treatment of idiopathic gynecomastia. We reviewed the clinical records of patients with idiopathic gynecomastia presenting to the Department of Surgery, University of Hong Kong, between August 1990 and September 1995. Medical treatment with either tamoxifen (20 mg/d) or danazol (400 mg/d) was offered and continued until a static response was achieved. The treatment response was compared. Sixty-eight patients with idiopathic gynecomastia were seen in the Breast Clinic. The median age was 39.5 years (range, 13-82), with a median duration of symptoms of 3 months (range, 1-90). The median size was 3 cm (range, 1-7). Twenty-three patients were treated with tamoxifen and 20 with danazol. Complete resolution of the gynecomastia was recorded in 18 patients (78.2%) treated with tamoxifen, whereas only 8 patients (40%) in the danazol group had complete resolution. Five patients, all from the tamoxifen group, developed recurrence of breast mass. In conclusion, hormonal manipulation is effective in the treatment of patients with idiopathic gynecomastia. Although the effect is more marked for tamoxifen compared with danazol, the relapse rate is higher for tamoxifen. Further prospective randomized studies would be useful in defining the role of these drugs in the management of patients with idiopathic gynecomastia.

Somatic mutations in the BRCA1 gene in Chinese sporadic breast and ovarian cancer

Inherited mutations in the BRCA1 gene confer increased susceptibility to breast and ovarian cancer. Its role in sporadic carcinogenesis is not well defined. Somatic mutations in breast cancers have not been reported and to date there are only three reports of somatic mutations in sporadic ovarian cancers. To investigate the contribution of BRCA1 mutations to sporadic breast and ovarian cancer in the Chinese population, we analysed 62 samples from Chinese women using the protein truncation test. There were 40 cases of breast cancer under age 50 and 22 cases of ovarian cancer, all unselected for family history. There was no age selection for the ovarian cancers. We found two somatic BRCA1 mutations in exon 11, one in a breast cancer and the other in an ovarian cancer, both of which result in truncated proteins. Our results indicate that somatic BRCA1 mutations, like somatic mutations in the BRCA2 gene, though very rare, can be found in both breast and ovarian cancers and support a tumor suppressor function for BRCA1 in sporadic tumors.

Clarithromycin attenuates the inflammatory response induced by surgical trauma in a guinea pig model

The effect of clarithromycin on the systemic and local inflammatory responses after surgical trauma was investigated using a guinea pig model. There was no statistically significant difference in the body temperature and respiratory rate of the guinea pigs between the clarithromycin and control groups, although there was a trend towards a lower temperature in the first 36 h after the operation, and a trend towards a lower respiratory rate on day 1 and day 2 (P=0.07 and 0.18, respectively) in the clarithromycin group. The total leukocyte count of both groups of animals increased from day -1 to day 4, and the increase was more marked in the control group (P=0.06 on day 1). The neutrophil and monocyte counts of the two groups of animals also increased after the operation. The neutrophil count of the control group was significantly higher than the clarithromycin group on day 1 and 2 (P<0.05 and 0.01, respectively), and the monocyte count of the control group was significantly higher than the clarithromycin group on day 1 (P<0.005). Moreover, the platelet count of the animals also increased after the operation, and the count in the control group was significantly higher than the clarithromycin group on day 1, 2 and 4 (P<0.05, 0.005 and 0.005, respectively). There was no difference between the haemoglobin concentration, lymphocyte count, eosinophil count and basophil count between the two groups of animals. The number of animals with wound discharge was lower in the clarithromycin group than the control group throughout the post-operative period, but the difference was not statistically significant. None of the animals developed signs of wound infection. The present observation suggests that clarithromycin suppressed both the systemic and local inflammatory response after surgical trauma, and it prompts further animal experiments for delineation of the mechanism of action, as well as clinical trials in major surgical procedures.

Amplification of GAA/TTC triplet repeat in vitro: preferential expansion of (TTC)n strand

Several human hereditary neuromuscular and neurodegenerative diseases are caused by abnormal expansion of triplet repeat sequences (TRSs) CAG/CTG, CGG/CCG, or GAA/TTC on certain chromosomes. It is generally accepted that multiple slippage synthesis accounts for the instabilities of TRS. Earlier in vitro experiments by Behn-Krappa and Doerfler showed that TRS with high GC content can be expanded. In contrast, here we demonstrated that certain AT-rich TRSs, (TTC)17, (GAA)10/(TTC)10 and (GAA)17/(TTC)17, were also expansion-prone in PCR. With respect to the sequence of TRS, surprisingly, we found that the AT-rich (GAA)17/(TTC)17 extended more efficiently than the GC-rich (CAG)17/(CTG)17. This strongly suggested that the AT content of the repeat may influence TRS expansion. Furthermore, to examine the expansion of single-stranded TRS, we showed that only (TTC)17, but not the complementary (GAA)17, can be expanded. This suggested that a T-T mismatch may stabilize compatible secondary structures, most likely hairpins, for slippage synthesis. However, another poly-pyrimidine TRS, (CCT)17, is not amplification-prone in PCR. Due to the high C-content, this TRS is unlikely to adopt hairpin structures at the high pH used for PCR. Thus, the single-stranded PCR experiment may serve as an indirect assay for the ability of a sequence to adopt a hairpin conformation. When amplification was performed in reactions using Klenow DNA polymerase, only the double-stranded TRSs can be expanded. The reaction rate for (GAA)10/(TTC)10 was slower than for (GAA)17/(TTC)17, suggesting that the length of the repeat may be important for the amplification of TRS. The findings of these in vitro experiments may aid in understanding TRS expansion in vivo.

Comparison of antiemetic efficacy of granisetron and ondansetron in Oriental patients: a randomized crossover study

A double-blind randomized crossover trial was performed to compare the antiemetic efficacy of two 5-HT3 receptor antagonists, granisetron and ondansetron, in Chinese patients receiving adjuvant chemotherapy (cyclophosphamide, methotrexate and 5-fluorouracil) for breast cancer. Twenty patients were randomized to receive chemotherapy with either granisetron on day 1 and ondansetron on day 8 of the first cycle followed by the reverse order in the second cycle, or vice versa. The number of vomiting episodes and the severity of nausea in the first 24 h (acute vomiting/nausea) and the following 7 days (delayed vomiting/nausea) were studied. Acute vomiting was completely prevented in 29 (72.5%) cycles with granisetron and 27 (67.5%) cycles with ondansetron, and treatment failure (>5 vomiting episodes) occurred in two (5%) cycles with each agent (P = NS). Acute nausea was completely controlled in 15 (37.5%) cycles with granisetron and 14 (35%) cycles with ondansetron, whereas severe acute nausea occurred in four (10%) cycles with each agent (P = NS). However, complete response for delayed vomiting was observed in only 21 (52.5%) cycles with granisetron and 22 (55%) cycles with ondansetron (P = NS), and delayed nausea was completely controlled in only 11 (27.5%) and ten (25%) cycles respectively (P = NS). In conclusion, both granisetron and ondansetron are effective in controlling acute nausea and vomiting in Chinese patients, with equivalent antiemetic efficacy. Control of delayed nausea and vomiting is less satisfactory.

Risk factors for rebleeding and death from peptic ulcer in the very elderly

BACKGROUND

Ageing populations are increasing in many countries and bleeding peptic ulcers in patients older than 60 years carry a greater risk of rebleeding and death. This study aimed to identify the risk factors for rebleeding and death in very elderly patients with peptic ulcer bleeding. The efficacy of treatment in preventing recurrent bleeding and death in this group of patients was also studied by means of prospective data collection and analysis.

METHODS

Data relating to 1744 patients treated between September 1985 and January 1994 for peptic ulcer bleeding were collected prospectively and analysed. Patients were stratified by age to one of three groups: group 1 (less than 60 years, n = 833), group 2 (60-79 years, n = 706) and group 3 (80 or more years, n = 205).

RESULTS

Univariate and multivariate analyses of 21 factors possibly affecting either rebleeding or death identified age greater than 80 years as one of the factors significantly affecting rebleeding and death. In a comparison of groups 1, 2 and 3, the likelihood of rebleeding and death was significantly greater in group 3. Univariate and multivariate analyses for rebleeding and death were performed for each group. The severity of initial bleeding had a marked bearing on subsequent rebleeding rates for all three groups. In group 3, however, large ulcer size and impaired liver function were additional factors which correlated significantly with final outcome. No rebleeding or morbidity occurred when endoscopic treatment was performed early for patients in group 3 but there was a significantly greater risk of further recurrent haemorrhage and treatment-related morbidity when treatment was performed after the onset of rebleeding.

CONCLUSION

Patients aged 80 years or greater had the highest risk of rebleeding and death. For patients below 80 years of age, significant factors related to a fatal outcome included co-morbid illness, complications and the need for mechanical ventilation. For patients aged 80 years or older, the significant factors were ulcer size greater than 2 cm and admission with serum bilirubin level above 20 mmol/l. Endoscopic treatment for the very elderly was effective if carried out early.

Expression of p53 in recurrent nodal metastasis from nasopharyngeal carcinoma (NPC)

This study reports the incidence of p53 expression in 40 patients with recurrent nodal metastasis from nasopharyngeal carcinoma (NPC) and its prognostic value in this group of patients. Immunohistochemical staining using monoclonal antibody specific for human p53 protein was performed on the tumour-bearing nodes from 40 patients. The results were divided into four grades (I, negative; II, < 10% of cells positive; III, 10-50% of cells positive; and IV, > 50% of cells positive). The staining scores were correlated with histological tumour types, subsequent recurrence and survival. All patients had undergone neck irradiation. Lymph node specimens from six patients (15%) showed positive staining of nuclear p53 protein. The distribution among the different grades was: three (7.5%) for II, two (5%) for III and one (2.5%) for IV. Patients with p53-overexpressed tumours had a significantly higher number of tumour-bearing lymph nodes. There was no correlation of p53 expression with histological tumour types, second tumour recurrence and survival. Expression of p53 appears to be uncommon in patients with recurrent nodal metastases in NPC. It did not have prognostic value in this particular series of patients.

Current status of breast cancer in Hong Kong

OBJECTIVE

To study the mode of presentation, the tumor, nodes, metastasis (TNM) staging and the efficacy of multimodal treatment of breast cancer among Chinese women treated in Queen Mary Hospital.

METHODS

The available records of all breast cancer patients treated between January 1980 and December 1994 were reviewed. The mode of presentation, the TNM staging of the disease, estrogen receptor status and the mode of surgical and adjuvant treatment were studied. Statistical correlation was performed between the factors studied and the survival time.

RESULTS

Seven hundred and one cases of breast cancer were identified. The mean age of the patients was 56.6 years (range, 20-98 years). The most common complaint was the presence of a mass which occurred in 635 (90.6%) patients and 454 (71.5%) of these patients were painless. The majority of patients had T2 tumours (51.8%) and stage II disease (59.6%), but only 86 (12.3%) patients underwent breast conservative therapy (BCT). Estrogen receptor was positive in 43% of patients. Two hundred and ninety (41.4%) patients were node positive and the mean number of involved nodes was 3.8 per patient. Adjuvant chemotherapy was given to 125 node positive patients, adjuvant tamoxifen to 188 patients and both to 63 patients. Univariate analyses of factors possibly affecting survival showed that advanced stage disease and nodal involvement were associated with a significantly lower survival time. Among the node positive patients, those with seven or more involved nodes had a shorter survival. The types of surgery and adjuvant treatment (for node positive patients) had no direct correlation with survival.

CONCLUSION

Our results showed that the majority of our patients presented with a painless mass and the final outcome was determined by the tumour load at the time of presentation (TNM staging and nodal status).