A nanofibrous spongy microsphere includes porous walls that define an exterior of the microsphere and that extend through an interior of the microsphere. The porous walls consist of interconnected nanofibers and spaces formed between the interconnected nanofibers. A plurality of micro-scale pores are formed throughout the interior of the microsphere. Each of the micro-scale pores i) is partially defined by the porous walls, ii) has an interpore opening that opens to an adjacent micro-scale pores, and iii) has a diameter ranging from about 1 μm to about 100 μm. A total diameter of the microsphere ranges from about 5 μm to about 1000 μm.