In this paper we briefly introduce some microdevices which have been developed recently for biomedical applications by micro-fabrication technology. These applications mainly include areas of diagnostics, drug delivery, tissue engineering and minimally-invasive surgery.
Biomedical Engineering ; instrumentation ; methods ; Clinical Laboratory Techniques ; instrumentation ; methods ; Drug Delivery Systems ; instrumentation ; methods ; Equipment Design ; Humans ; Microsurgery ; instrumentation ; Miniaturization ; Tissue Engineering ; instrumentation ; methods

Tissue engineering technology provides a new method to repair ill tissue and worn-out organs. In tissue engineering, scaffolds play an important role in supporting cell growth, inducing tissue regeneration, controlling tissue structure and releasing active factor. In the last decade, electrospinning technology developed rapidly and opened vast application fields for scaffolds. In this review, we summarized the technological conditions of electrospinning for scaffolds, the study of electrospun fiber scaffolds applied in tissue cell cultivation, and some new directions of electrospinning technology for scaffolds. We also addressed development directions of electrospinning research for scaffolds.
Absorbable Implants ; Biocompatible Materials ; chemistry ; Electrochemistry ; methods ; Guided Tissue Regeneration ; Tissue Engineering ; instrumentation ; methods ; Tissue Scaffolds ; chemistry

Nanostructured materials are gaining new impetus owing to the advancements in material fabrication techniques and their unique properties (their nanosize, high surface area-to-volume ratio, and high porosity). Such nanostructured materials mimic the subtleties of extracellular matrix (ECM) proteins, creating artifi cial microenvironments which resemble the native niches in the body. On the other hand, the isolation of mesenchymal stem cells (MSCs) from various tissue sources has resulted in the interest to study the multiple differentiation lineages for various therapeutic treatments. In this review, our focus is tailored towards the potential of biomimetic nanostructured materials as osteoinductive scaffolds for bone regeneration to differentiate MSCs towards osteoblastic cell types without the presence of soluble factors. In addition to mimicking the nanostructure of native bone, the supplement of collagen and hydroxyapatite which mimic the main components of the ECM also brings signifi cant advantages to these materials.
Biomimetics ; instrumentation ; methods ; Bone Transplantation ; Collagen Type I ; Extracellular Matrix ; Humans ; Mesenchymal Stromal Cells ; Nanostructures ; Osteogenesis ; Tissue Engineering ; instrumentation ; methods

Electrospinning is a very effective way to prepare scaffolds for biomedical applications. However, conventional electrospinning technique has shortcomings for this purpose. Modification studies on electrospinning technique have been conducted by more and more researchers. This paper summaries the research progress in electrospinning technique for biomedical materials.
Biocompatible Materials ; chemical synthesis ; Elasticity ; Electrochemistry ; instrumentation ; methods ; Materials Testing ; Nanostructures ; chemistry ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry

Increasing incidence of musculoskeletal injuries coupled with limitations in the current treatment options have necessitated tissue engineering and regenerative medicine- based approaches. Moving forward from engineering isolated musculoskeletal tissues, research strategies are now being increasingly focused on repairing and regenerating the interfaces between dissimilar musculoskeletal tissues with the aim to achieve seamless integration of engineered musculoskeletal tissues. This article reviews the state-of-the-art in the tissue engineering of musculoskeletal tissue interfaces with a focus on Singapore's contribution in this emerging field. Various biomimetic scaffold and cellbased strategies, the use of growth factors, gene therapy and mechanical loading, as well as animal models for functional validation of the tissue engineering strategies are discussed.
Cell- and Tissue-Based Therapy ; Genetic Therapy ; Humans ; Intercellular Signaling Peptides and Proteins ; Musculoskeletal Diseases ; rehabilitation ; therapy ; Orthopedic Procedures ; instrumentation ; methods ; Osteogenesis ; Regenerative Medicine ; instrumentation ; methods ; Singapore ; Stem Cells ; Stress, Mechanical ; Tissue Engineering ; instrumentation ; methods ; Tissue Scaffolds ; Weight-Bearing

OBJECTIVETo evaluate the influence of adipose tissue extract on inducing angiogenesis and adipogenesis in adipose tissue engineering chamber in vivo.

METHODS6 months' healthy New Zealand rabbits (n = 64) were picked. The inguinal fat pads were cultured, centrifuged, filtered, and the liquid was called adipose tissue extract (ATE). Two adipose tissue engineering chamber were built in the rabbit's back. A week later, 0.2 ml normal saline (control group, left) and 0. 2 ml ATE (experimental group, right) was respectively injected into the chamber. The contents were evaluated morphometrically, histologically and immunohistochemically 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks and 7 weeks after injection. 8 rabbits were observed each time. The data regarding the number of the volume of fat flap and blood capillary at each time point were analyzed by paired t test.

RESULTSAfter injection, new tissue volume was significantly increased in the experimental group [(5.12 ± 0.22) ml], compared with that in control group [(4.90 ± 0.15) ml]. Early angiogenesis was also increased after ATE injection and the total number of capillaries reached peak 1 week after injection, which was (72.80 ± 9.67) in experimental group and (51.40 ± 6.09) in control group. In the mid-term of experimental period, earlier adipogenesis appeared in experimental group. In the later period, the outer capsule of the new construction was thinner in experimental group which reduced the suppression of the adipogenesis.

CONCLUSIONSATE can promote the angiogenesis and adipogenesis in the chamber, and reduce the capsule contracturing, so as to induce the large volume of adipose tissue regeneration

Adipogenesis ; drug effects ; physiology ; Adipose Tissue ; chemistry ; physiology ; Animals ; Neovascularization, Physiologic ; drug effects ; Rabbits ; Regeneration ; Tissue Engineering ; instrumentation ; Tissue Extracts ; pharmacology

The ideal treatment and recovery of osteoarticular injury remain to be resolved. Small intestinal submucosa (SIS), a naturally-occurring decellularized extracellular matrix, has been recognized as an ideal scaffold for tissue engineering and widely used in repairing various tissues and organs. Nowadays its application has also been gradually increased in the field of orthopedics. We reviewed laboratorial studies and clinical trails about the application of SIS in bone and joint repair, aiming to evaluate its effects on the repair of bone, cartilage, meniscus, ligament and tendon. SIS has showed promising results in repairing bone, meniscus, ligament or tendon. However, additional studies will be required to further evaluate its effects on articular cartilage and tendon-bone healing. How to optimize SIS material,is also a focused problem concerned with making SIS a potential therapeutic option with high value for orthopedic tissue repair.
Animals ; Cell- and Tissue-Based Therapy ; Humans ; Intestinal Mucosa ; cytology ; Intestine, Small ; cytology ; Joint Diseases ; physiopathology ; surgery ; therapy ; Tissue Engineering ; instrumentation ; methods ; Tissue Scaffolds ; chemistry

Three-dimensionally controlled cell-assembly technique makes fabricating tissues and organs in vitro to be possible. However, for real tissues and organs with complex structure and various cells, fabricating tissues and organs in vitro need a technique that could assemble and locate multi cells and materials precisely in the space. Facing the needs of multi-cell assembly, we designed a mixer nozzle and the matching pulse switching circuit which based on the single-nozzle cell assembly system, and developed a multi-cell-assembly system. We also carried out some assembly experiments with this system using materials that were similar to the multi-component extracellular matrix materials. The results demonstrated that the system could assemble various cells and materials into three-dimensional inhomogeneous structures precisely.
Bioartificial Organs ; Cell Culture Techniques ; instrumentation ; Cell Physiological Phenomena ; Equipment Design ; methods ; Extracellular Matrix ; chemistry ; Humans ; Tissue Engineering ; methods

BACKGROUNDEndothelial and smooth muscle cells were used as seeding cells and heterogeneous acellularized matrix was used as scaffold to construct the tissue-engineered graft.

METHODSA 2 weeks piglet was selected as a donor of seeding cells. Two-centimetre length of common carotid artery was dissected. Endothelial cells and smooth muscle cells were harvested by trypsin and collagenase digestion respectively. The isolated cells were cultured and expanded using routine cell culture technique. An adult sheep was used as a donor of acellularized matrix. The thoracic aorta was harvested and processed by a multi-step decellularizing technique to remove the original cells and preserve the elastic and collagen fibers. The cultured smooth muscle cells and endothelial cells were then seeded to the acellularized matrix and incubated in vitro for another 2 weeks. The cell seeded graft was then transplanted to the cell-donated piglet to substitute part of the native pulmonary artery.

RESULTSThe cultured cells from piglet were characterized as endothelial cells by the presence of specific antigens vWF and CD31, and smooth muscle cells by the presence of specific antigen alpha-actin on the cell surface respectively with immunohistochemical technique. After decellularizing processing for the thoracic aorta from sheep, all the cellular components were extracted and elastic and collagen fibers kept their original morphology and structure. The maximal load of acellular matrix was decreased and 20% lower than that of untreated thoracic aorta, but the maximal tensions between them were not different statistically and they had similar load-tension curves. Three months after transplantation, the animal was sacrificed and the graft was removed for observation. The results showed that the inner surfaces of the graft were smooth, without thrombosis and calcification. Under microscopy, a great number of growing cells could be seen and elastic and collagen fibers were abundant.

CONCLUSIONCultured self-derived endothelial and smooth muscle cells could be used as seeding cells and heterogeneous acellularized matrix could be used as scaffold in constructing tissue-engineered graft.

Animals ; Cell Differentiation ; Cell Transplantation ; Cells, Cultured ; Graft Survival ; Sheep ; Swine ; Tissue Engineering ; instrumentation ; methods ; Transplantation, Heterologous

A rotating perfusion bioreactor system has recently been developed in our laboratory to produce 3D dynamic culture condition, and the critical-sized scaffolds with interconnected microchennels were fabricated. Gas exchange occurs by semipermeable membrane covered on each side of bioreactor and gas-permeable peristaltic pump tube. Rotation and perfusion of culture media through large scaffolds enhance well mixing and mass transport of oxygen and nutrients in the bioreactor. Osteoblastic cells attached to microchennels are exposed to a low fluid flow-induced shear stress level. This bioreactor system overcomes several defects exited in static culture condition, improves the culture environment, facilitates osteoblast proliferation, differntiation, significant matrix production and mineralization, and the controllability of culture process is enhanced. Large scaffolds/osteoblast constructs were cultured in the bioreactor system for 14 days. Osteoblastic cells attached to microchannels of scaffolds were observed under scanning electron microscope (SEM). The results indicated that cells grew extensively in the microchennels of large scaffolds.
Animals ; Animals, Newborn ; Bioreactors ; Cell Culture Techniques ; instrumentation ; methods ; Cell Differentiation ; Osteoblasts ; cytology ; Rabbits ; Skull ; cytology ; Tissue Engineering ; methods ; Tissue Scaffolds