Chan K Y, Järveläinen M, Chang J H, Edenfield M J
Department of Ophthalmology, University of Washington School of Medicine, Seattle.
Invest Ophthalmol Vis Sci. 1990 Oct;31(10):2008-21.
This study used a transcorneal freezing technique to produce a 2-mm circular, central wound in the rabbit cornea for investigating corneal nerve regeneration. All the corneal cells, nerves, and associated Schwann cells were dead inside the wound, but the extracellular matrix components remained intact. The destroyed epithelium and endothelium were replaced in 1 and 5-7 days, respectively. The necrotic keratocytes and stromal and subepithelial nerves were removed completely in 1-3 days by invading macrophage-like cells. The wounded stroma was repopulated centripetally by migrating keratocytes between days 1-5. Two types of nerve growth were identified in the stroma. The first type was novel sprouting of straight, long neurites between days 2-21, initially from the undamaged, periwound nerves and later from regenerated stromal nerves inside the wound. These small-caliber neurites proliferated in a random and disorderly pattern both inside and outside the wound and sometimes terminated on stationary, stellate keratocytes. The second type was genuine regrowth of stromal and subepithelial nerves in a centripetal direction between days 3-7. Schwann cells appeared on the newly formed nerves starting on day 4 or 5. A near-normal pattern and size of the nerves were established in the wound as early as day 10. In the epithelium, transient, wound-oriented neurites (days 1-3), single nerves, and semileashes (days 4-10) appeared. A near-normal leash pattern was restored between days 10-21 only at the wound periphery. Thus, in this model, the major groundwork of nerve regeneration occurred between days 3-10, simultaneously, at all three levels of nerve organization. These data suggest that nerve-Schwann cell interaction contributes to the restoration of stromal and subepithelial nerves, whereas a reparative epithelium deficient in trophic activity may account for the incomplete regrowth of epithelial nerves. The cryodamage model offers an efficient and multifaceted system for the experimental study of corneal nerve regeneration.
本研究采用经角膜冷冻技术在兔角膜上制作一个2毫米的圆形中央伤口，以研究角膜神经再生。伤口内所有角膜细胞、神经及相关施万细胞均死亡，但细胞外基质成分保持完整。受损的上皮和内皮分别在1天和5 - 7天内得到替换。坏死的角膜细胞以及基质和上皮下神经在1 - 3天内被侵入的巨噬细胞样细胞完全清除。在第1 - 5天，迁移的角膜细胞向心填充受伤的基质。在基质中鉴定出两种神经生长类型。第一种类型是在第2 - 21天之间，从最初未受损的伤口周围神经，随后从伤口内再生的基质神经长出的笔直、长神经突的新生芽。这些小口径神经突在伤口内外以随机且无序的模式增殖，有时终止于静止的星状角膜细胞。第二种类型是在第3 - 7天之间，基质和上皮下神经沿向心方向真正的再生。施万细胞在第4天或第5天开始出现在新形成的神经上。早在第10天，伤口处的神经就建立了接近正常的模式和大小。在上皮中，出现了短暂的、面向伤口的神经突（第1 - 3天）、单根神经和半束状神经（第4 - 10天）。仅在伤口周边，在第10 - 21天之间恢复了接近正常的束状模式。因此，在该模型中，神经再生的主要基础工作在第3 - 10天之间同时在神经组织的所有三个层面发生。这些数据表明，神经 - 施万细胞相互作用有助于基质和上皮下神经的恢复，而缺乏营养活性的修复性上皮可能是上皮神经再生不完全的原因。冷冻损伤模型为角膜神经再生的实验研究提供了一个高效且多方面的系统。
