Manufacturing HDMACs. (a) BM-MSCs were isolated from bone marrow liquid aspirated from rabbits. After expansion, re-suspension, and incubation, the cells spontaneously aggregated into a spheroid-like structure. Each scale unit represents 1 μm. (b) A handmade tube-shaped Teflon mold with a diameter of 4.6 mm and a height of 5 mm. The spheroids described in (a) were loaded into this mold. Each scale unit represents 1 mm. (c) The tube-shaped mold was maintained under air-liquid interface conditions and incubated for a week. These loaded spheroids fused with each other, and a cylinder-shaped construct made with fused cells was obtained according to the inner shape of the mold. Each scale unit represents 1 mm. (d) Safranin O staining of HDMACs after 1 week of incubation. Scale bar =100 μm. (N = 1).