Biomedical Engineering: Applications, Basis and Communications

Apoptosis is an erratic physiological process whereby cells undergo a self-destruction process. A quantitative analysis of apoptosis, namely counting the number of cells undergoing apoptosis, is required not only to understand the mechanism of this process but also to quantitatively evaluate the effect of anticancer drugs as many anticancer drugs attempt to achieve their effects by inducing the cancer cell to apoptosis. Currently, counting cells undergoing apoptosis is generally carried out manually by the naked eyes. Although these methods are accurate and appropriate in some cases, they can be extremely time consuming and labor intensive. Also, manual counting is subjective and difficult to achieve high throughput. There is compelling necessity for developing an automatic apoptosis-counting method. In this paper, we described an image-based method, which is applied in HCT116 human colon adenocarcinoma cell culture to count the number of apoptosis induced by anticancer drug oxaliplatin. Our methods are mostly based on well-known and mature algorithms in image processing and pattern recognition such as the contrast-limited adaptive histogram equalization, pixel classification, size distribution detection by granulometries, watershed algorithm, and artificial neural networks. We evaluated our segmentation results using the area overlap measurement, and the best achieved performance that can reach over 98%. We also evaluated our apoptosis detection results against the results of four biomedical experts and compared the results with other existing efforts. The final performance shows that our method is more reliable and accurate for detecting apoptosis than the previous methods.

Far infrared rays (FIRs) have several proven effects on the human body and are generally considered to be biologically beneficial. In this study, we determined the effect of FIRs on hydrogen peroxide (H₂O₂)-scavenging activity, which was directly increased by 10.26% after FIR application. Even in the indirect use of FIRs accompanying carrot extract, FIRs still contributed to a 5.48% increase in H₂O₂-scavenging activity. We further proved that additional FIR treatment resulted in about 23.02% and 18.77% viability increases of osteoblast cells in the 200 and 800 μM H₂O₂, respectively; and about 25.67% and 47.16% viability increases of fibroblast cells in the 25 and 50 μM H₂O₂, respectively. Finally, FIR treatment also delayed senescence of detached Railway Beggarticks leaves in H₂O₂ solution with the concentrations of 10, 100, and 1000 μM. By reviewing past articles related to the effects of oxidative stress from metabolically produced H₂O₂, we discuss possible benefits of FIRs for plants and animals.

Hydroxyapatite (HAp) is the major inorganic component in human bones and well known for its biocompatibility. It has been widely prepared in many forms for orthopedic and dental applications. Color-center-doped HAps are also prevalently used as fluorescent materials. Further, HAp based photoluminescent material might be an ideal agent for bioimaging. Moreover, self-assembly of HAp in calcium- and phosphate-containing solutions gains a lot of attention because organic–inorganic HAp hybrids can be tailor-made. In this study, the author used a biomimetic process to synthesize organic–inorganic HAp nano hybrid at room temperature. The natural and synthesized polymeric templates used to prepare the organic–inorganic HAp hybrids were collagen, PEG–PLGA (di block), and PEG–PLGA–PEG (tri block), respectively. X-ray diffraction (XRD) diagrams revealed that the synthesized powders had crystalline HAp phase, and transmission electron microscope (TEM) photographs showed their nano grain structure. Characterization using XRD, TEM, and Fourier transform infrared spectrometer (FTR) indicated the existence of crystalline HAp phase and the variation in HAp shape versus different polymers in the composite powders. The measurement of photoluminescent (PL) spectra used a 325 nm He–Cd laser as source. The di HAp and tri HAp emitted light with a wide range of wavelength from 350 to 550 nm, much stronger than pure HAp. Collagen alone emitted brighter fluorescence peaked around 410 nm but was quickly quenched, while collagen–HAp composite powders emitted sustaining PL light peaking around 415 nm. The developed PL bioceramics are of great potential in bio sensing and bio optoelectronics.

Gelatin-based drug carrier matrices have emerged as very promising class of delivery system. The purpose of this investigation was to develop drug loaded gelatin-based gels (composites). Gelatin matrices were crosslinked with genipin, a naturally occurring crosslinker for the release of indomethacin. Indomethacin, a low molecular weight and moderately hydrophobic, anti-inflammatory agent was incorporated into the gelatin matrices to form drug loaded gel composites for the release study. The gels were subjected to temperature-dependent oscillatory rheology. The result showed pouring temperature in the range of ~31–34°C for the un-crosslinked gels while the crosslinked gels did not show crossover point. Gels were studied for surface morphology using scanning electron microscopy and a porous network structure was observed. The release of indomethacin from the gels indicated an initial increase in the release rate with the increase in drug concentrations. It was observed that drug composites with higher drug concentration exhibited higher drug transport. Swelling and crosslinking played a crucial role in regulating the drug transport. Further, viability assay suggested biocompatibility of these matrices in vitro. Gel in vitro cell compatibility using live dead assay evaluated with AH-927 cell line indicated normal cell proliferation without any harmful effect and thus suggesting appropriateness of crosslinked composites as potential drug carrier.

The retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. The native RPEs exist as a monolayer structure and have a mottled brown color due to the presence of melanin and other pigments including lipofuscin granules, which accumulate with age. In age-related macular degeneration (AMD), RPE's dysfunction and changes in Bruch's membrane occur. Thus, small intestine submucosa/poly(lactic-co-glycolic acid) (SIS/PLGA) film is a biomimetic transplant consisting of a layer of healthy RPE cells cultured on a support membrane. The goals of this study were to evaluate the effects of attachment and proliferation of RPEs on SIS/PLGA films. Porcine SIS is an acellular tissue and widely used as a biomaterial without immunorejection responses, whereas PLGA is a biodegradable synthetic polymer with acceptable mechanical strength and well-controlled degradation rate. We fabricated SIS/PLGA films using 20 wt% of SIS. We measured MTT to confirm cellular adhesion of cell number attached on film at 1, 3, 5, and 7 days. Morphology of cellular adhesion on films was confirmed by scanning electron microscopy at 1, 3, and 7 days. Further, reverse transcription polymerase chain reaction (RT-PCR) was conducted to confirm messenger RNA expression of RPE65 as RPE's marker and expression of cytokeratin, and RPE65 were determined by AEC immunocytochemical staining. These results suggest that SIS provides suitable surface to RPEs.

Aim. Macroporous sponge-like gelatin–hyaluronic acid (Gl–HA) scaffolds cross-linked by EDC were produced using cryogelation technology, which allows for the preparation of highly porous scaffolds without compromising their mechanical properties, and is a more cost-efficient process than freeze drying. The aim of this study is to evaluate the osteogenic potential of porcine adipose-derived stem cells (PADSCs) in GI–HA cryogel.

Method. The character of the GI–HA cryogel was evaluated. The pore size and the microstructure were observed using scanning electron microscope (SEM). The swelling ratio was measured. The PADSCs were harvested and isolated from pig inguinal area. Then, the GI–HA cryogel was seeded with PADSCs. The cryogel/ASCs mixture was cultured in osteogenic medium for 0, 3, 7, 14, and 21 days. The cell proliferation was measured by MTS. The RT-PCR of specific osteogenic gene expression such as osteocalcin (OC), RUNX2 was used to assess the osteogenic ability. The SEM was used to observe the interaction between scaffold and cells. Energy dispersive spectrum (EDS) was used to analyze the mineralization around cells.

Results. The pore size was variable between 200 and 369 μm. The swelling ratio was around 8.67 ± 1.669%. The cell proliferation was increasing along with the increase of induction periods. The expression of early gene of RUNX2 and late gene of OC mean that the PADSCs were differentiated well into osteoblasts within the cryogels. The SEM detailed that the PADSCs cell can proliferate well in the pore of GI–HA scaffold. The EDS also demonstrated the mineralization of PADSCs in GI–HA scaffold after induction.

Conclusions. To conclude, the PADSCs can proliferate and differentiate well into osteoblasts in the three-dimensional, porous, GI–HA cryogel.

The main objective of this study is to characterize the in vitro osteo inductive behavior of pearl nano crystallites. The results obtained from X-ray diffraction, Fourier transform infrared (FTIR) spectra, and inductively coupled plasma mass (ICP-MS) analysis demonstrate that the pearls can induce the formation of a hydroxyl apatite (HA) layer on their surface in simulated body fluid (SBF), even after only short soaking periods. Further, MC3T3-E1 cells can easily attach and spread on the pearl powders after 1 h of cultivation.

Gold nanoparticles (GNPs) are widely used in chemical sensing, drug delivery, biomedical imaging, and photothermal therapy due to their strong and size-tunable surface plasmon resonance, fluorescence, and easy-surface functionalization. In this study, we investigated the effects of water-dispersed GNPs on the cytotoxicity and differentiation of human bone marrow mesenchymal stem cells (hBMSCs) and the associated death pathway. The results showed that the viability of hBMSCs was dependent upon the size of GNPs. Further, GNPs at the smallest size exhibited the highest cytotoxicity after treatment for 5 days and also substantially suppressed the number of colony-forming unit-fibroblast (CFU-F) of hBMSCs after continuous exposure for 21 days. Although large and medium sizes of GNPs had minor cytotoxicity to the cells, the sizes of CFU-F formed in the groups treated with GNPs at medium and large sizes were smaller compared to the control group. Further study of the cell death pathway using GNPs at medium size found that GNPs triggered hBMSCs necrosis, possibly by oxidative stress after GNPs were endocytosed. In addition, GNPs exerted the inhibitory effects on induced osteogenesis and adipogenesis of hBMSCs. Alkaline phosphatase (ALP) activity and calcium mineralization during osteogenic induction as well as the accumulation of triacylglycerides in adipogenic hBMSCs were repressed significantly by coculturing with GNPs at medium size. Our results suggest that the application of GNPs as long-term tracers for the activities of mesenchymal stem cells (MSCs) should be carefully evaluated.

Silicone hydrogels with interpenetrating network (IPN) structure were prepared by ultraviolet (UV)-initiated simultaneous free-radical/cationic polymerizations in order to develop contact lens with high performances. The polymerization mechanism was investigated by gel fraction method using polymerization of 2-hydroxyethyl methacrylate (HEMA) and 4-hydroxybutyl vinyl ether (HBVE) as a model. The results showed that HEMA and crosslinker ethylene glycol dimethacrylate (EGDMA) polymerized by free-radical mechanism, while HBVE and crosslinker triethylene glycol divinyl ether (DVE-3) polymerized by cationic mechanism. The IPN silicone hydrogels were then prepared by UV-initiated hybrid photopolymerization of monomers including HEMA and bitelechelic polydimethylsiloxane bearing vinyl ethers end-groups (VS) in the presence of free-radical and cationic photoinitiators. Physiochemical properties such as optical properties, ion permeability, contact angle, and mechanical properties of the silicone hydrogels were characterized by UV spectroscopy, ionoflux technique, and tensile tester. The results revealed that the water content, surface wettability, and ion permeability of the hydrogels increased, but the tensile strength and Young's modulus decreased with the increase of the HEMA content.