Clem Jones Centre for Regenerative Medicine, Bond University, Gold Coast, QLD, 4229, Australia.
Bioessays. 2019 May;41(5):e1800234. doi: 10.1002/bies.201800234. Epub 2019 Apr 10.
Bone marrow is the main site for hematopoiesis in adults. It acts as a niche for hematopoietic stem cells (HSCs) and contains non-hematopoietic cells that contribute to stem cell dormancy, quiescence, self-renewal, and differentiation. HSC also exist in resting spleen of several species, although their contribution to hematopoiesis under steady-state conditions is unknown. The spleen can however undergo extramedullary hematopoiesis (EMH) triggered by physiological stress or disease. With the loss of bone marrow niches in aging and disease, the spleen as an alternative tissue site for hematopoiesis is an important consideration for future therapy, particularly during HSC transplantation. In terms of harnessing the spleen as a site for hematopoiesis, here the remarkable regenerative capacity of the spleen is considered with a view to forming additional or ectopic spleen tissue through cell engraftment. Studies in mice indicate the potential for such grafts to support the influx of hematopoietic cells leading to the development of normal spleen architecture. An important goal will be the formation of functional ectopic spleen tissue as an aid to hematopoietic recovery following clinical treatments that impact bone marrow. For example, expansion or replacement of niches could be considered where myeloablation ahead of HSC transplantation compromises treatment outcomes.
骨髓是成人造血的主要部位。它充当造血干细胞（HSCs）的龛位，并包含有助于干细胞休眠、静止、自我更新和分化的非造血细胞。HSC 也存在于几种物种的静止脾脏中，尽管它们在稳态条件下对造血的贡献尚不清楚。然而，脾脏可以通过生理应激或疾病引发骨髓外造血（EMH）。随着衰老和疾病中骨髓龛位的丧失，脾脏作为造血的替代组织部位是未来治疗的一个重要考虑因素，特别是在 HSC 移植期间。就利用脾脏作为造血部位而言，这里考虑了脾脏的显著再生能力，以期通过细胞移植形成额外的或异位的脾脏组织。在小鼠中的研究表明，这种移植物有可能支持造血细胞的涌入，从而导致正常脾脏结构的发育。一个重要的目标是形成功能性异位脾脏组织，以帮助在影响骨髓的临床治疗后造血恢复。例如，可以考虑在 HSC 移植前进行骨髓清除术以损害治疗效果的情况下扩大或替代龛位。
