The immunological response of macrophages to physically produced pure Au and Ag nanoparticles (NPs) (in three different sizes) is investigated in vitro. The treatment of either type of NP at > or =10 ppm dramatically decreases the population and increases the size of the macrophages. Both NPs enter the cells but only AuNPs (especially those with smaller diamter) up-regulate the expressions of proinflammatory genes interlukin-1 (IL-1), interlukin-6 (IL-6), and tumor necrosis factor (TNF-alpha). Transmission electron microscopy images show that AuNPs and AgNPs are both trapped in vesicles in the cytoplasma, but only AuNPs are organized into a circular pattern. It is speculated that part of the negatively charged AuNPs might adsorb serum protein and enter cells via the more complicated endocytotic pathway, which results in higher cytotoxicity and immunological response of AuNPs as compared to AgNPS.

No abstract

In this study, a series of natural biodegradable materials in the form of chitosan (C)-alginate (A)-hyaluronate (H) complexes are evaluated as tissue-engineering scaffolds. The weight ratio of C/A is 1 : 1 or 1 : 2. Sodium hyaluronate is mixed in 2%. The complexes can be cast into films or fabricated as scaffolds. Their surface can be further modified by an Arg-Gly-Asp (RGD)-containing protein, a cellulose-binding domain-RGD (R). Cytocompatibility tests of the films are conducted using immortalized rat chondrocyte (IRC) as well as primary articular chondrocytes harvested from rabbits. The neocartilage formation in cell-seeded scaffolds is examined in vitro as well as in rabbits, where the scaffolds are implanted into the defect-containing joints. The results from cytocompatibility tests demonstrate that R enhances cell attachment and proliferation on C-A and C-A-H complex films. Complex C1A1HR (C : A = 1 : 1 with H and R) has better performance than the other formulation. Cells retain their spherical morphology on all C-A and C-A-H complexes. The in vitro evaluation of the seeded scaffolds indicates that the C1A1HR complex is the most appropriate for 3-D culture, manifested by the better cell growth as well as higher glycosaminoglycan and collagen contents. When the chondrocyte scaffolds are implanted into rabbit knee cartilage defects, partial repair is observed after 1 month in C1A1HR as well as in C1A1 (C : A = 1 : 1 without H and R) scaffolds. The defects are completely repaired in 6 months when C1A1HR constructs are implanted. It is concluded that C1A1HR is a potential tissue-engineering scaffold for cartilage regeneration.

We describe a biomimetic mode of insoluble signaling stimulation to provide target delivery of bone morphogenetic protein-2 (BMP-2), with the aim of prolonging the retention of BMP-2 use in bone tissue engineering and to enable its localized release in response to cellular activity. In our novel localization process, we used heterobifunctional acrylate-N-hydroxysuccinimide poly(ethylene glycol) (PEG) as a spacer to tether BMP-2 onto a poly(lactide-co-glycolide) scaffold. Use of PEG-tethered BMP-2 was feasible because BMP-2 retained its activity after covalent conjugation. The PEG-tethered BMP-2 conjugate sustained stimulation and retained its mitogenic activity, notably affecting pluripotent stem cell proliferation and differentiation. We seeded the scaffolds with bone marrow-derived mesenchymal stromal cells as progenitor cells to evaluate their morphology and phenotypic expression. We also created bilateral, full-thickness cranial defects in rabbits to investigate the osteogenic effect of cultured mesenchymal stromal cells on bone regeneration in vivo. Histomorphometry and histology demonstrated that the PEG-tethered BMP-2 conjugate enhanced de novo bone formation after surgery. Our work revealed the potential for biomimetic surface engineering by entrapping signaling growth factor to stimulate osteogenesis. Our technique may provide a new platform for bone-engineered stem cell therapies.

Novel technologies, such as those described in this study, including photopolymerization and tissue engineering, may provide minimally invasive therapeutic procedures via arthroscopy to enhance biological healing after reconstruction of the anterior cruciate ligament.

Due to the potential for increasing ocean temperatures to detrimentally impact reef-building corals, there is an urgent need to better understand not only the coral thermal stress response, but also natural variation in their sub-cellular composition. To address this issue, while simultaneously developing a molecular platform for studying one of the most common Taiwanese reef corals, Seriatopora hystrix, 1,092 cDNA clones were sequenced and characterized. Subsequently, RNA, DNA and protein were extracted sequentially from colonies exposed to elevated (30°C) temperature for 48 hours. From the RNA phase, a heat shock protein-70 (hsp70)-like gene, deemed hsp/c, was identified in the coral host, and expression of this gene was measured with real-time quantitative PCR (qPCR) in both the host anthozoan and endosymbiotic dinoflagellates (genus Symbiodinium). While mRNA levels were not affected by temperature in either member, hsp/c expression was temporally variable in both and co-varied within biopsies. From the DNA phase, host and Symbiodinium hsp/c genome copy proportions (GCPs) were calculated to track changes in the biological composition of the holobiont during the experiment. While there was no temperature effect on either host or Symbiodinium GCP, both demonstrated significant temporal variation. Finally, total soluble protein was responsive to neither temperature nor exposure time, though the protein/DNA ratio varied significantly over time. Collectively, it appears that time, and not temperature, is a more important driver of the variation in these parameters, highlighting the need to consider natural variation in both gene expression and the molecular make-up of coral holobionts when conducting manipulative studies. This represents the first study to survey multiple macromolecules from both compartments of an endosymbiotic organism with methodologies that reflect their dual-compartmental nature, ideally generating a framework for assessing molecular-level changes within corals and other endosymbioses exposed to changes in their environment.

No abstract

Highly porous poly(D,L-lactide-co-glycolide) (PLGA) scaffolds for cartilage tissue engineering were fabricated in this study using the fused deposition manufacturing (FDM) process and were further modified by type II collagen. The average molecular weight of PLGA decreased to about 60% of the original value after the melt-extrusion process. Type II collagen exhibited sponge-like structure and filled the macroporous FDM scaffolds. An increase of the fiber spacing resulted in an increase of the porosity. The storage modulus of FDM scaffolds with a large fiber spacing was comparable to that of the native porcine articular cartilage. Although the FDM hybrid scaffolds were swollen in various extents after 28 days of in vitro culture, the seeded chondrocytes were well distributed in the interior of the scaffolds with a large fiber spacing and neocartilage was formed around the scaffolds. The study also suggested that a low processing temperature may be required to produce PLGA precision scaffolds using FDM.