Sisk M A, Lohmann C H, Cochran D L, Sylvia V L, Simpson J P, Dean D D, Boyan B D, Schwartz Z
Department of Orthopaedics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
Clin Oral Implants Res. 2001 Feb;12(1):52-61. doi: 10.1034/j.1600-0501.2001.012001052.x.
Prostaglandin E2 (PGE2) and transforming growth factor-beta 1 (TGF-beta 1) production are increased in cultures of osteoblasts grown on rough surfaces and prostaglandins are involved in osteoblast response to surface roughness. In the present study, we examined the effect of inhibiting cyclooxygenase on this response. MG63 osteoblast-like cells were cultured on cpTi disks with Ra values of 0.60 micron (PT), 3.97 microns (SLA), and 5.21 microns (TPS) in the presence or absence of 10(-7) M indomethacin. Treatment was begun on days 1, 2, 3, or 4 after seeding, and all cultures were harvested on day 5. Indomethacin decreased PGE2 release by the cells to less than 50% of basal levels when the cells were cultured on plastic. Cell number decreased with increasing surface roughness and indomethacin treatment abrogated the surface roughness effect over time. Alkaline phosphatase specific activity (ALP) increased with surface roughness; after one day with indomethacin, ALP was decreased on smooth surfaces, but increased on rough surfaces. Over time, ALP decreased on all surfaces examined and remained greater than plastic only in cultures on TPS. Indomethacin also caused a time-dependent decrease in osteocalcin production on rough surfaces, eventually abrogating the increases due to surface roughness, but had no effect on osteocalcin production on smooth surfaces. TGF-beta 1 levels in the cell layer and media were sensitive to surface roughness; on rougher surfaces, TGF-beta 1 shifted from the media to the matrix. Indomethacin reduced TGF-beta 1 levels over time, but the surface roughness effect was still evident at 4 days. This indicates that prostaglandin production mediates the effects of surface roughness, since indomethacin causes a time-dependent abrogation of the response, but has no effect on proliferation, osteocalcin release, or TGF-beta 1 levels on smooth surfaces. Indomethacin's effect was not immediate, suggesting that clinical protocols could be designed that would reduce inflammation without preventing osteoblastic differentiation. The effect of indomethacin was not complete, since TGF-beta 1 and ALP remained elevated on rough surfaces, suggesting that pathways or factors other than prostanoids are involved. TGF-beta 1 is preferentially stored in the matrix, acting on the cells through autocrine signaling, and may contribute to ALP even in the presence of indomethacin. These results demonstrate the importance of local factors in the autocrine regulation of osteogenesis and the potential for factors released in response to surface morphology to act in a paracrine manner.
在粗糙表面上培养的成骨细胞中，前列腺素E2（PGE2）和转化生长因子-β1（TGF-β1）的产生增加，并且前列腺素参与成骨细胞对表面粗糙度的反应。在本研究中，我们研究了抑制环氧化酶对这种反应的影响。在存在或不存在10^(-7)M吲哚美辛的情况下，将MG63成骨样细胞培养在粗糙度平均高度（Ra）值分别为0.60微米（PT）、3.97微米（SLA）和5.21微米（TPS）的纯钛盘上。接种后第1、2、3或4天开始处理，所有培养物在第5天收获。当细胞在塑料上培养时，吲哚美辛将细胞释放的PGE2降低至基础水平的50%以下。细胞数量随着表面粗糙度的增加而减少，吲哚美辛处理随着时间的推移消除了表面粗糙度的影响。碱性磷酸酶比活性（ALP）随着表面粗糙度的增加而增加；用吲哚美辛处理一天后，光滑表面上的ALP降低，但粗糙表面上的ALP增加。随着时间的推移，所有检查表面上的ALP均降低，并且仅在TPS表面上培养的细胞中，其水平仍高于在塑料上培养的细胞。吲哚美辛还导致粗糙表面上骨钙素的产生随时间减少，最终消除了由于表面粗糙度引起的增加，但对光滑表面上的骨钙素产生没有影响。细胞层和培养基中的TGF-β1水平对表面粗糙度敏感；在较粗糙的表面上，TGF-β1从培养基转移到基质中。吲哚美辛随着时间的推移降低了TGF-β1水平，但在第4天时表面粗糙度的影响仍然明显。这表明前列腺素的产生介导了表面粗糙度的影响，因为吲哚美辛会随时间消除这种反应，但对光滑表面上的细胞增殖、骨钙素释放或TGF-β1水平没有影响。吲哚美辛的作用不是即时的，这表明可以设计临床方案来减少炎症而不阻止成骨细胞分化。吲哚美辛的作用并不完全，因为粗糙表面上的TGF-β1和ALP仍然升高，这表明除类前列腺素之外的其他途径或因子也参与其中。TGF-β1优先储存在基质中，通过自分泌信号作用于细胞，并且即使在存在吲哚美辛的情况下也可能对ALP有贡献。这些结果证明了局部因子在成骨自分泌调节中的重要性，以及响应表面形态而释放的因子以旁分泌方式起作用的潜力。
