Giovanini Allan Fernando, Grossi João Ricardo Almeida, Gonzaga Carla Castiglia, Zielak João Cesar, Göhringer Isabella, Vieira Juliana de Souza, Kuczera Juliane, de Oliveira Filho Marco Antonio, Deliberador Tatiana Miranda
Masters Program in Clinical Dentistry, Positivo University, Curitiba, Brazil.
Clin Implant Dent Relat Res. 2014 Apr;16(2):259-72. doi: 10.1111/j.1708-8208.2012.00478.x. Epub 2012 Jul 16.
Leukocyte-platelet-rich plasma (L-PRP) is considered an important source of growth factors, especially Transforming growth factor β 1 (TGF-β1), which modulates the proliferation and regulation of mesenchymal cells, and also exerts an influence on the hematopoiesis, osteogenesis, and adipogenesis in bone microenvironment. Thus, the aim of this study was to evaluate the effect of L-PRP on the calvarial bone repair and compare its results on the presence of TGF-β1, CD34, CD45, bone morphogenetic protein 2 (BMP2), BMPR1B, and Runx2 proteins detected by immunohistochemistry.
Four bone defects were created on the calvaria of 23 rabbits. The defects were treated with autograft, L-PRP alone, and L-PRP mixed with autograft. The animals were euthanized at 2, 4, and 6 weeks post-surgery.
Unlike autograft and sham groups, the defects treated with L-PRP demonstrated significant positivity to TGF-β1, while the BMP2 was scarce. These results coincided with the lower bone matrix deposited and larger medullary area, which were composed of fibrosis, when treated with only L-PRP, or intense adiposity on defects filled with L-PRP mixed with autograft. The fibrosis that occurred was associated with a minor percentage of osteoproteins, intense presence of CD34(+) CD45(-) cells, and significant expression of TGF-β1 in all time periods analyzed. The adiposity occurred from the major presence of osteoprogenitor BMPR1B (+) Runx2(+) cells simultaneously to BMP2(-) TGF-β1(+) and CD34(+) CD45(+/-) expressions predominantly on the earlier period.
From this study, it can be concluded that the L-PRP used alone or mixed to autograft hindered the osteoneogenesis due to suppression of immunoexpression of BMP2, while the immunopositivity of TGF-β1 was intense. When used alone, the L-PRP induced a fibrotic condition associated with TGF-β1 presence and lack of osteoproteins, but when L-PRP was mixed to autograft, it induced the presence of the osteolineage cells (BMPR1B (+) Runx2(+) ), but also inhibited the terminal osteoblastic maturation associated with the lack of BMP2 and the presence of TGF-β1(+) , a fact that contributed to cellular transdifferentiation into fat cells.
富含白细胞-血小板血浆（L-PRP）被认为是生长因子的重要来源，尤其是转化生长因子β1（TGF-β1），它可调节间充质细胞的增殖和调控，还对骨微环境中的造血、成骨和脂肪生成产生影响。因此，本研究旨在评估L-PRP对颅骨修复的作用，并通过免疫组织化学检测比较其对TGF-β1、CD34、CD45、骨形态发生蛋白2（BMP2）、BMPR1B和Runx2蛋白表达的影响。
在23只兔子的颅骨上制造四个骨缺损。这些缺损分别用自体骨移植、单独的L-PRP以及L-PRP与自体骨移植混合进行治疗。术后2周、4周和6周对动物实施安乐死。
与自体骨移植组和假手术组不同，用L-PRP治疗的缺损对TGF-β1显示出显著阳性，而BMP2较少。这些结果与仅用L-PRP治疗时较低的骨基质沉积和较大的髓腔面积相符，髓腔面积由纤维化组成，或者在L-PRP与自体骨移植混合填充的缺损处出现严重脂肪沉积。所发生的纤维化与少量的骨蛋白、大量CD34(+) CD45(-)细胞的存在以及在所有分析时间段内TGF-β1的显著表达相关。脂肪沉积主要源于早期同时存在大量骨祖细胞BMPR1B(+) Runx2(+)细胞以及主要为BMP2(-) TGF-β1(+)和CD34(+) CD45(+/-)的表达。
从本研究可以得出结论，单独使用或与自体骨移植混合使用的L-PRP由于抑制了BMP2的免疫表达而阻碍了骨生成，而TGF-β1的免疫阳性较强。单独使用时，L-PRP诱导了与TGF-β1存在和骨蛋白缺乏相关的纤维化状态，但当L-PRP与自体骨移植混合使用时，它诱导了骨系细胞（BMPR1B(+) Runx2(+)）的存在，但也抑制了与BMP2缺乏和TGF-β1(+)存在相关的终末成骨细胞成熟，这一事实导致细胞转分化为脂肪细胞。
