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Biomaterial is one of the most important factors to be developed in regenerative medicine. In this paper, the biomaterials essential to regenerative medicine were described. Biomaterials in regenerative medicine are classified into 5 categories; 1) Biomaterials for cell culture, 2) Biomaterials for cell inducement, 3) Biomaterials for scaffold, 4) Biomaterials for immuno-isolation, 5) Biomaterials assist to regenerative medicine. As for 1), temperature responsible gel that can take out the cultured cell sheet without use protein breakdown enzyme, is mainly introduced. Micro-photolithography to make a micro patterning for cell inducement, kinds of materials for scaffold, isolated membrane and micro capsules, carrier for cell growth factors are mentioned in 2) to 5).

We aimed to develop a method of accurately identifying the dorsal root for the corresponding peripheral afferent nerve under endoscopic observation. We developed an endoscope with an external diameter of 1.8 mm. After small laminectomy on the lower thoracic vertebrae, we inserted this endoscope carefully into the epidural and then subarachnoid spaces. We observed structures in these spaces with the endoscope. We tried to determine the spatial relationship between these electrodes and dorsal root. After identifying each space, we inserted two electrodes into the visualized space to record evoked potentials; a bipolar electrode (protocol 1) and a catheter-type eight polar electrode (protocol 2). Each pole could be distinguished by marks. To stimulate peripheral nerves, we inserted needle-type electrodes into Th 10, 11 and 12 intercostal nerves. We attempted to record potentials from dorsal surface of the cord generated by intercostal nerve stimulus. Protocol 1: We moved the position of the bipolar recording electrodes between Th 9 and L 1 by 1 cm increment, and obtained evoked potentials correspondingly. Protocol 2: We chose the neighboring pairs of poles sequentially from the tip of the catheter for bipolar recording. At the end of each experiment, we dissected the animal and checked the intercostal nerve originating from the root. With the endoscope, we could clearly observe structures in the epidural and subarachnoid spaces. We could record evoked potentials from the dorsal spinal cord with the electrodes located either in epidural or in subarachnoid spaces. Shapes of evoked potentials changed characteristically according to the relative position between the root and the electrode. The largest potentials were obtained when the electrode was nearest to the dorsal root, of which the peripheral nerve was being stimulated. By combining endoscopy with the electrophysiological technique, we could accurately identify the dorsal roots for the corresponding peripheral afferent nerves. This method may be used for the selective dorsal root blockade under the visual field.

What are the most essential technologies for developing the implantable artificial heart in future? The first is the development of autonomic and dispersed micro actuators for acting as sarcomeres of the heart muscle. An electric motor driven artificial heart transmitted the power with belts had been developed as a preliminary mechanism. A micro actuation using noise energy has been developed for simulating the structure and the function of striate-muscle sarcomeres. The chemical energy conversion mechanism must be applied instead of the conventional electro-mechanical mechanisms, when we implant the total artificial heart permanently. As a implantable assisted artificial heart using tentatively, we have developed an axial flow pump system. The pump system acts as a systemic and a pulmonary pump produced pulsatile flow switching an axial pump output. The second is the search of biocompatible materials, which do not only mean blood compatibility but also tissue compatibility. The great masses in chest cavity have inevitably occurred infection. The autonomic and dispersed control system is the third item. We have developed a jellyfish valve with low fluid dynamical resistances for improving the pump dynamic characteristics.

We developed control system of total artificial heart (TAH) during exercise simulating the circulatory response of natural heart. The following procedures were taken to develop this system. 1) Measurement of hemodynamics and physical activity rate (PAR) of natural heart goats during treadmill exercise. 2) Estimation of cardiac output from PAR using a non-linear model. 3) Development of a pneumatic artificial heart (AH) driver with high speed controllability and a control unit to deliver CO calculated from PAR beat by beat. 4) Evaluation of the physiological condition of the TAH goat during exercise controlled by this system. Using this control method, CO of TAH goats was similar to that of natural heart goats during treadmill exercise. Hypertension was observed during exercise. This hypertension was considered to be derived from two causes. One was high inflow and outflow resistance of cannulae between AH pump and living body. The other was the disorder of peripheral circulatory control mechanism in TAH animal. Such as increased sympathetic activity, insufficient secretion of atrial natriuretic polypeptide (ANP) and decreased sensitivity of peripheral circulatory system with ANP.

We began applying of our VAD system clinically in 1982 and have subsequently obtained good results. The first case treated with the VAD returned to normal life. In a total of 70 cases of clinical applications this system there has been instance of apparatus dysfunction. Confirming the reliability and safety promised by the results of biological experiments. Here, we report the results of clinical application of the system in a total of 61 cases between August, 1985 and March, 1989. The following conclusions were reached: 1) Satisfactory weaning and survival rates were obtained i.e. 18 cases out of 61 cases (30%) survived over one month and 13 cases (21%) are currently surviving, even in elderly patients of 60 years of age or older. 2) The weaning rate and survival rates were good after approximately 1 week of support. Detailed evaluation of the recovery of the heart and functions of other major organs has led to the conclusion that the results can be improved further when the weaning period is carefully determined. 3) With regard to surgical factors, good findings were obtained when the artificial heart-lung bypass time was less than 6 hours. The VAD can be used in the early stages without vainly attempting weaning from the artificial heart-lung bypass. 4) There were no mechanical problems with the hardware of the blood pump drive assembly, etc., or noteworthy side effects.