We recently developed a promising regenerative method based on the xenotransplantation of human cartilage progenitor cells, demonstrating self-renewing elastic cartilage reconstruction with expected long-term tissue restoration. However, it remains unclear whether autotransplantation of cartilage progenitors may work by a similar principle in immunocompetent individuals. We used a nonhuman primate (monkey) model to assess the safety and efficacy of our regenerative approach because the model shares characteristics with humans in terms of biological functions, including anatomical features. First, we identified the expandable and multipotent progenitor population from monkey ear perichondrium and succeeded in inducing chondrocyte differentiation in vitro. Second, in vivo transplanted progenitor cells were capable of reconstructing elastic cartilage by xenotransplantation into an immunodeficient mouse. Finally, the autologous monkey progenitor cells were transplanted into the subcutaneous region of a craniofacial section and developed mature elastic cartilage of their own 3 months after transplantation. Furthermore, we attempted to develop a clinically relevant, noninvasive monitoring method using magnetic resonance imaging (MRI). Collectively, this report shows that the autologous transplantation of cartilage progenitors is potentially effective for reconstructing elastic cartilage. This principle will be invaluable for repairing craniofacial injuries and abnormalities in the context of plastic and reconstructive surgery.

Microtia is a congenital aplasia of the auricular cartilage. Conventionally, autologous costal cartilage grafts are collected and shaped for transplantation. However, in this method, excessive invasion occurs due to limitations in the costal cartilage collection. Due to deformation over time after transplantation of the shaped graft, problems with long-term morphological maintenance exist. Additionally, the lack of elasticity with costal cartilage grafts is worth mentioning, as costal cartilage is a type of hyaline cartilage. Medical plastic materials have been transplanted as alternatives to costal cartilage, but transplant rejection and deformation over time are inevitable. It is imperative to create tissues for transplantation using cells of biological origin. Hence, cartilage tissues were developed using a biodegradable scaffold material. However, such materials suffer from transplant rejection and biodegradation, causing the transplanted cartilage tissue to deform due to a lack of elasticity. To address this problem, we established a method for creating elastic cartilage tissue for transplantation with autologous cells without using scaffold materials. Chondrocyte progenitor cells were collected from perichondrial tissue of the ear cartilage. By using a multilayer culture and a three-dimensional rotating suspension culture vessel system, we succeeded in creating scaffold-free elastic cartilage from cartilage progenitor cells.

Secondary upper limb lymphoedema is usually caused by lymphatic system dysfunction. Diagnosis is primarily based on clinical features. However, there are no distinct diagnostic criteria for lymphoedema. Although conventional lymphoscintigraphy is a useful technique to diagnose the severity of lymphoedema, the resultant data are two-dimensional. In this study, we examined the pathology of lymphoedema using single photon emission computed tomography-computed tomography lymphoscintigraphy (SPECT-CT LSG), a new technique that provides 3-dimensional information on lymph flow. We observed lymph flow pathways in the subcutaneous and muscle layers of the upper limbs. A significant positive correlation was found between the dermal back flow (DBF) type and the visualization of lymph nodes around the clavicle ( p = 0.000266), the type of lymph flow pathways and the visualization of lymph nodes around the clavicle ( p = 0.00963), and the DBF type and the lymph flow pathway (p = 0.00766). As the severity of lymphoedema increased, the DBF appeared more distally in the upper limb and the flow into the lymph nodes around the clavicle decreased, whereas the lymph flow pathways in the muscle layer became dominant. These findings demonstrate the features of lymphoedema pathology and the functional anatomy and physiology of the lymphatic system without the need for cadaver dissection.

Morphologically stable scaffold-free elastic cartilage tissue is crucial for treating external ear abnormalities. However, establishing adequate mechanical strength is challenging, owing to the difficulty of achieving chondrogenic differentiation in vitro; thus, cartilage reconstruction is a complex task. Auricular perichondrial chondroprogenitor cells exhibit high proliferation potential and can be obtained with minimal invasion. Therefore, these cells are an ideal resource for elastic cartilage reconstruction. In this study, we aimed to develop a novel in vitro scaffold-free method for elastic cartilage reconstruction, using human auricular perichondrial chondroprogenitor cells. Inducing chondrogenesis by using microscopic spheroids similar to auricular hillocks significantly increased the chondrogenic potential. The size and elasticity of the tissue were maintained after craniofacial transplantation in immunodeficient mice, suggesting that the reconstructed tissue was morphologically stable. Our novel tissue reconstruction method may facilitate the development of future treatments for external ear abnormalities.

Sequential programs and high pressure resulted in a faster lymphatic flow than other modes. These results suggest that a greater treatment effect could be obtained by adjusting the mode of treatment and the pressure of IPC.