‘Regenerative Engineering’ is the integration of advanced materials science, stem cell science, physics, developmental biology and clinical translation to regenerate complex tissues and organ systems. Advanced biomaterial and stem cell science converge as mechanisms to guide regeneration and the development of prescribed cell lineages from undifferentiated stem cell populations. Studies in somite development and tissue specification have provided significant insight into pathways of biological regulation responsible for tissue determination, especially morphogen gradients, and paracrine and contact-dependent signaling. The understanding of developmental biology mechanisms are shifting the biomaterial design paradigm by the incorporation of molecules into scaffold design and biomaterial development that are specifically targeted to promote the regeneration of soft tissues. Our understanding allows the selective control of cell sensitivity, and a temporal and spatial arrangement to modulate the wound healing mechanism, and the development of cell phenotype leading to the patterning of distinct and multi-scale tissue systems.

Building on the development of mechanically compliant novel biomaterials, the integration of spatiotemporal control of biological, chemical and mechanical cues helps to modulate the stem cell niche and direct the differentiation of stem cell lineages. We have developed advanced biomaterials and biomimetic scaffold designs that can recapitulate the native tissue structure and mechanical compliance of soft musculoskeletal tissues, such as woven scaffold systems for ACL regeneration, non-woven scaffolds for rotator cuff tendon augmentation, and porous elastomers for regeneration of muscle tissue. Studies have clearly demonstrated the modulation of stem cell response to bulk biomaterial properties, such as toughness and elasticity, and scaffold structure, such as nanoscale and microscale dimensions. The integration of biological cues inspired from our understanding of developmental biology, along with chemical, mechanical and electrical stimulation drives our development of novel biomaterials aimed at specifying the stem cell lineage within 3-dimensional (3D) tissue systems. This talk will cover the development of biological cues, advanced biomaterials, and scaffold designs for the regeneration of complex soft musculoskeletal tissue systems such as ligament, tendon, and muscle.

We have investigated plant growth response to atmospheric air plasma treatments of seeds on their growth for 5 plant speces; Radish sprout (Raphanus sativus L.), rice (Oryza Sativa), Zinnia, Arabidopsis L. Thaliana and Plumeri. The average length of Radish sprout, rice, Arabidopsis Thaliana, Plumeria and Zinnia, are 250%, 80%, 60%, 30% and 20% longer than those without plasma treatments, respectively. We have obtained correlation between the growth enhancement and O3 and NOx concentration. The optimum radical dose for the growth enhancement depends on plant species.

Recently, commercial home electric appliances with bactericidal/viral inactivation function of room air have been widely available. Most of these home appliances equip discharge devices which possibly generate reactive oxygen and nitrogen oxides. However, these effects are still controversial problem. To elucidate the inactivation effect of these devices at molecular level, we have been considering large DNA molecules as a biomarker to be used. By exposing DNA solution to the gas containing the chemical species, oxidative damage to DNA such as strand breaks can be induced. We have conducted the single-molecule-based evaluation method of DNA strand break using large linear DNA molecules. The obtained breakage rate could possibly be used for evaluation of reactivity of radicals generated by the discharge devices.

Calcium phosphate cements show self-hardening reaction upon mixing with liquids to form calcium-deficient hydroxyapatite (CDHA) or dicalcium phosphate dihydrate. The effects of particle sizes, crystallinities, and natural polymers such as tilapia scale collagen (Col) and hyaluronic acid as a dispersant on the mechanical properties of alpha tricalcium phosphate (TCP) cements mixed with citric acid (CA) as an additive were investigated. Three types of alpha TCP particles were fabricated with spray-dry (SD; 14 μm), freeze-dry (FD; 45 μm), and cold isostatic press (CIP; 134 μm) methods, followed by sintering at 1300°C and ground/crushed. The amounts of Ca dissolution from these particles were in the order of SD > FD > CIP. The CA liquid was added to the powders of SD-FD or SD-CIP, and kneaded under different liquid/powder ratios. The cements containing CIP particles showed lower compressive strength at 22.9 ± 1.5 MPa than those containing FD particles at 28.3 ± 2.5 MPa, even though the apparent densities of the cements containing CIP material was higher. Although the packing density of powders is an important factor on the mechanical properties of cements, the dissolution of Ca ion has a greater impact on the mechanical properties. The addition of Col into the cements increased the mechanical properties at 33.6 ± 2.5 MPa at 1 day to enhance the re-precipitation of CDHA.

Collagen is the most abundant protein present in the human body and found in connective tissues, bone, and tendon. It is also known as a natural resource for healing damaged skin tissues [1]. In this study, under specific microenvironment conditions, mimetic collagen gels were successfully formed synthetically from reconstituted Bovine type I collagen monomers. This was achieved by controlling ionic strength, temperature and pH, allowing fibrils with native mimetic D periodic banding structure to assemble spontaneously within the gels. In addition, by providing appropriate aging temperatures and times, mature collagen fibril growth is also realized in the gels in vitro. Mimetic gels were subsequently formed into fibers through a wet-spinning process. These spun fibers were found to preserve the native mimetic D periodic banding and fibrillar structure formed in the initial gels. As a result, the synthetic fibers resemble native tendon. Here structural development within the gel samples and fibers as a function of processing was analyzed by scanning electron microscopy (SEM). Results in this study also show a potentially new route for the fabrication of synthetic collagen fibers mimicking tendon, which may find applications as engineered tissues or scaffolding materials.

Poly(ε-caprolactone) (PCL) biopolymer nano- and micro-fibers have been fabricated at high rates up to 14.0 grams per hour using a needleless and collectorless alternating current electrospinning technique. By combining the ac-voltage, glacial acetic acid (AA) as the solvent and sodium acetate (NaAc) as an additive, beadless PCL fibers with diameters tunable from 150 nm to 2000 nm, varying surface morphology and degree of self-bundling were obtained. In this new approach, the addition of NaAc plays a crucial role in improving the spinnability of PCL solution and fiber morphology. NaAc revealed the concentration-dependent effect on charge transfer and rheological properties of the PCL/AA precursor, which results in broader ranges of spinnable PCL concentrations and ac-voltages suitable for rapid manufacturing of PCL-based fibers with different textural properties.

Due to injuries and disease, there is a great need for a robust, biocompatible, biodegradable, skin-like dermal substitute to repair and regenerate damaged or lost skin. A novel electrochemical process was used to fabricate planarly aligned, densely packed collagen-based sheet which closely mimics the major structure of collagen in skin. The collagen matrix was characterized by scanning electron microscopy (SEM), oxygen permeation, moisture vapor transmission rate (MVTR), and mechanical strength. The seeding and proliferation of adipose derived stem cells (ADSCs) on the matrix was also evaluated. The results indicate that electrochemically-aligned collagen matrix has good MVTR, superior oxygen permeability, and is robust and biocompatible. Thus, it will be evaluated in vivo in the near future as a dermal substitute material.

Nanoparticles have great potential for biomedical applications such as early detection, accurate diagnosis, and personalized treatment of cancer. Assessment of bio-compatibility and toxicity of nanoparticles body is an emerging topic for these applications. To study kinetics of nanoparticles in body, we synthesized indium, gold and platinum nanoparticles in aqueous suspension using pulsed electrical discharge plasmas in water. The average size of synthesized primary nanoparticles for indium, gold, and platinum are 6.2 nm, 6.7 nm, and 5.4 nm, whereas the average size of secondary nanoparticles for indium, gold, and platinum are 315 nm, 72.3 nm, and 151 nm, respectively. Synthesized indium nanoparticles are transported from subcutaneous to serum and brain. The indium content in serum for the synthesized nanoparticles is much higher than that for the In2O3 nanoparticles of 150 nm in primary size. For gold and platinum nanoparticles, preliminary examination of intratracheal administration revealed that administration of synthesized nanoparticles with 10 mg/kg BW (body weight) may cause bleedings and/or emphysema in lung.

The present paper contains results of the experimental researches of structure properties of the catalytic coating based on the nanoporous TiO2 film affected by corona-discharge plasma in air atmosphere under atmospheric pressure in the test system of needle-plane electrodes. Coating of the plate electrode was found to influence insignificantly on the discharge current-voltage characteristic, however if there is a coating on the plane electrode surface, an offset is observed towards lower currents under constant voltage at the gap. Obtained data on the surface morphology change shows that under negative corona erosion of the nanoporous TiO2 coating surface is practically absent and under positive corona, decrease of the coating thickness is observed.