Sequential delivery of immunomodulatory cytokines to facilitate the M1-to-M2 transition of macrophages and enhance vascularization of bone scaffolds

In normal tissue repair, macrophages exhibit a pro-inflammatory phenotype (M1) at early stages and a pro-healing phenotype (M2) at later stages. We have previously shown that M1 macrophages initiate angiogenesis while M2 macrophages promote vessel maturation. Therefore, we reasoned that scaffolds that promote sequential M1 and M2 polarization of infiltrating macrophages should result in enhanced angiogenesis and healing. To this end, we first analyzed the in vitro kinetics of macrophage phenotype switch using flow cytometry, gene expression, and cytokine secretion analysis. Then, we designed scaffolds for bone regeneration based on modifications of decellularized bone for a short release of interferon-gamma (IFNg) to promote the M1 phenotype, followed by a more sustained release of interleukin-4 (IL4) to promote the M2 phenotype. To achieve this sequential release profile, IFNg was physically adsorbed onto the scaffolds, while IL4 was attached via biotin-streptavidin binding. Interestingly, despite the strong interactions between biotin and streptavidin, release studies showed that biotinylated IL4 was released over 6 days. These scaffolds promoted sequential M1 and M2 polarization of primary human macrophages as measured by gene expression of ten M1 and M2 markers and secretion of four cytokines, although the overlapping phases of IFNg and IL4 release tempered polarization to some extent. Murine subcutaneous implantation model showed increased vascularization in scaffolds releasing IFNg compared to controls. This study demonstrates that scaffolds for tissue engineering can be designed to harness the angiogenic behavior of host macrophages towards scaffold vascularization.     

骨髓基质细胞移植促进大鼠局灶性脑损伤血管生成的实验研究

目的研究骨髓基质细胞（BMSCs）移植对大鼠局灶性脑损伤血管生成的影响，探讨BMSCs移植修复大鼠脑损伤的机制。方法制备大鼠局灶性脑损伤动物模型，进行BMSCs移植，通过免疫组织化学、电镜等观察移植局部内皮细胞及微循环的变化。结果BMSCs移植后，局部凝血因子FⅧ染色阳性细胞数增加，染色加深，出现血管样结构；局部微血管内膜较光滑，内皮细胞间可见紧密连接，细胞核形态较规则，基底膜较完整，微血管管腔受压缓解。结论BMSCs移植促进损伤区周围内皮细胞增殖和新生血管形成。损伤区局部微循环得以改善进而修复脑损伤。     

生物衍生骨复合骨髓基质干细胞修复山羊胫骨缺损的血管化研究

目的研究生物衍生骨与骨髓基质干细胞(marrow stromal stem cells, MSCs)复合修复山羊胫骨缺损的血管化过程,了解其修复长段管状负重骨缺损的血管化情况. 方法制备生物衍生骨作为支架材料,培养、诱导MSCs作为种子细胞,二者在体外复合构建组织工程骨.20只山羊双侧胫骨中段制备成20 mm长的骨-骨膜缺损模型,采取自身左右侧对照,实验侧(右侧)缺损处植入组织工程骨,对照侧(左侧)植入单纯支架材料,采用钢板内固定.术后2、4、6及8周用墨汁灌注透明标本及血管面积图像分析方法观察血管化过程,组织学观察血管形成及成骨情况. 结果术后2、4周,实验侧血管形成较对照侧少(P<0.05);术后8周,两侧均完全血管化,差异无统计学意义(P>0.05).实验侧于术后6、8周新骨形成逐渐增加,材料降解吸收较对照组快;对照侧术后8周材料孔隙内仍无明显新骨形成. 结论生物衍生骨作为骨组织工程的支架材料,能够较快发生血管化;组织工程骨成骨能力较单纯支架材料强.     

Expression and distribution of vascular endothelial growth factor protein in human brain tumors

Marked neovascularization is a hallmark of many neoplasms in the nervous system. Recent reports indicate that the endothelial mitogen vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation in malignant gliomas. Using novel monoclonal antibodies to the VEGF polypeptide we have determined the expression and cellular distribution of VEGF protein in a representative series of 171 human central nervous system (CNS) tumors by immunohistochemistry and immunoblotting. In agreement with previous in situ hybridization data, 19 out of 20 glioblastomas (95%) showed immunoreactivity for VEGF, whereas both the percentage of immunoreactive tumors and the extent of immunoreactivity for VEGF were significantly lower in astrocytomas. Of the pilocytic astrocytomas (WHO grade I) 44% were immunoreactive for VEGF, but we observed several cases with pronounced vascular proliferates in the absence of VEGF. In ependymomas, meningiomas, hemangioblastomas, and primitive neuroectodermal tumors, there was no correlation between VEGF expression, vascular endothelial proliferation and the grade of malignancy. Oligodendrogliomas and the oligodendroglial component of mixed gliomas lacked immunoreactive VEGF, indicating that endothelial growth factors other than VEGF may regulate tumor angiogenesis in these neoplasms. Western blot analysis showed a predominant VEGF protein species of 23 kDa and confirmed the immunohistochemical data in all cases. Our findings demonstrate that VEGF is expressed in a wide spectrum of brain tumors in which it may induce neovascularization. However, other angiogenic factors also appear to contribute to the vascularization of CNS neoplasms. Received: 18 April 1996 / Revised, accepted: 20 August 1996     

Upper tibial corticocancellous flap anatomy study (19.2.93)

Summary A cortico-cancellous flap from the anterolateral aspect of the upper third of the tibia was presented. Sixty lower limbs of fresh cadavers were dissected. The vascular bundle includes the anterior tibial artery and its recurrent collateral branches and recurrent and muscllo periostal arteries. The flap is harvested with the interosseous membrane and can be used either free or pedicled. We used this flap for two patients suffering from pseudarthrosis. Long range clinical and radiological results are good.

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Le transfert osseux vascularisé tibial superieur

Résumé Les auteurs décrivent un transfert ostéo-periosté vascularisé, prélevé sur la face antéro-latérale de l'extremité supérieure du tibia. L'étude anatomique porte sur soixante membres inférieurs, conservés au froid. La vascularisation métaphysaire du transfert provient de la branche récurrente tibiale antérieure et de ses rameaux, la vascularisation diaphysaire étant issue des branches musculo-périostiées proximales. Le transfert vascularisé est prélevé avec la membrane interosseuse et peut être pediculé ou libre. L'expérience clinique porte sur deux cas de pseudarthroses multiopérées. Les résultats cliniques et radiologiques sont bons à long terme.

     

Vascular networks of the nucleus lentiformis

Summary The nucleus lentiformis vascular networks were studied in 30 brains by injecting the vascular system with gelatinous Indian ink. The nucleus lentiformis is divided into a medial part, the globus pallidus, and a lateral part, the putamen. These two parts differ completely from one another in their embryology, structure and functions. For these reasons, each part presents a specific vascular network. The putaminal network is dense and shows many similarities with the cerebral cortex vascular network; the pallidal one is simpler and less dense. These two vascular networks are located close to each other without overlapping. Their specificity may be in relation with the histological structure, with the morphogenetic evolution or with the functional activity of both nuclei to which they provide the vascularization.

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Les réseaux vascularies du noyau lenticulaire

Résumé L'étude des réseaux vasculaires du noyau lenticulaire (NL) est réalisée sur 30 cerveaux dont le système vasculaire a été injecté à l'encre de Chine gélosée. Le NL est constitué par deux parties, le putamen (néostriatum) et le globus pallidus (paléo-striatum), totalement différentes sur les plans morphologique, embryologique et fonctionnel. Chacune de ces parties possède un réseau vasculaire spécifique et caractéristique. Les deux réseaux se côtoient sans se chevaucher. Le réseau vasculaire putaminal est dense et présente de nombreuses similitudes avec le réseau vasculaire du cortex cérébral. Le réseau vasculaire pallidal se caractérise par sa simplicité et sa moindre densité. Leur spécificité peut être en rapport avec la structure histologique, l'évolution morphogénétique et avec l'activité fonctionnelle des noyaux dont ils assurent l'irrigation.

     

In vivo cellular reactions to different biomaterials—Physiological and pathological aspects and their consequences

Biomaterials are widely used in guided bone regeneration (GBR) and guided tissue regeneration (GTR). After application, there is an interaction between the host immune system and the implanted biomaterial, leading to a biomaterial-specific cellular reaction. The present review focuses on cellular reactions to numerous biomaterials in vivo with consideration of different implantation models and microenvironments in different species, such as subcutaneous implantation in mice and rats, a muscle model in goats and a femur model in rabbits. Additionally, cellular reactions to different biomaterials in various clinical indications within the oro-maxillofacial surgical field were considered. Two types of cellular reactions were observed. There was a physiological reaction with the induction of only mononuclear cells and a pathological reaction with the induction of multinucleated giant cells (MNGCs). Attention was directed to the frequently observed MNGCs and consequences of their appearance within the implantation region. MNGCs have different subtypes. Therefore, the present review addresses the different morphological phenotypes observed within the biomaterial implantation bed and discusses the critical role of MNGCs, their subtypes and their precursors as well as comparing the characteristics and differences between biomaterial-related MNGCs and osteoclasts. Polymeric biomaterials that only induced mononuclear cells underwent integration and maintained their integrity, while polymeric biomaterials that induced MNGCs underwent disintegration with material breakdown and loss of integrity. Hence, there is a question regarding whether our attention should be directed to alternative biological concepts, in combination with biomaterials that induce a physiological mononuclear cellular reaction to optimize biomaterial-based tissue regeneration.     

Shell-core bi-layered scaffolds for engineering of vascularized osteon-like structures

Bottom-up assembly of osteon-like structures into large tissue constructs represents a promising and practical strategy toward the formation of hierarchical cortical bone. Here, a unique two-step approach, i.e., the combination of electrospinning and twin screw extrusion (TSE) techniques was used to fabricate a microfilament/nanofiber shell–core scaffold that could precisely control the spatial distribution of different types of cells to form vascularized osteon-like structures. The scaffold contained a helical outer shell consisting of porous microfilament coils of polycaprolactone (PCL) and biphasic calcium phosphates (BCP) that wound around a hollow electrospun PCL nanofibrous tube (the core). The porous helical shell supported the formation of bone-like tissues, while the luminal surface of nanofibrous core enabled endothelialization to mimic the function of Haversian canal. Culture of mouse pre-osteoblasts (POBs, MC 3T3-E1) onto the coil shells revealed that coils with pitch sizes greater than 135 μm, in the presence of BCP, favored the proliferation and osteogenic differentiation of POBs. The luminal surface of PCL nanofibrous core supported the adhesion and spreading of mouse endothelial cells (ECs, MS-1) to form a continuous endothelial lining with the function similar to blood vessels. Taken together, the shell–core bi-layered scaffolds with porous, coil-like shell and nanofibrous tubular cores represent a new scaffolding technology base for the creation of osteon analogs.     

Vasculogenesis and angiogenesis in nonseminomatous testicular germ cell tumors

Testicular germ cell tumors (TGCTs) comprise the vast majority of all testicular malignancies and are the most common type of cancer among young male adults. The nonseminomatous variant of TGCTs is characterized by the presence of embryonic and extraembryonic tissues together with a population of pluripotent cancer stem cells, the so-called embryonal carcinoma. One of the main causes of the resistance of these tumors to therapy is their ability to invade adjacent tissues and metastasize into distant sites of the body. Both of these tumor processes are highly favored by the neovascularization of the malignant tissue. New vessels can be generated by means of angiogenesis or vasculogenesis, and both have been observed to occur during tumor vascularization. Nevertheless, the precise contribution of each process to the neoplastic vascular bed of TGCTs remains unknown. In addition, another process known as tumor-derived vasculogenesis, in which malignant cells give rise to endothelial cells, has also been reported to occur in a number of tumor types, including experimental TGCTs. The participation and cross talk of these 3 processes in tumor vascularization is of particular interest, given the embryonic origin of teratocarcinomas. Thus, in the present review, we discuss the importance of all 3 vascularization processes in the growth, invasion, and metastasis of testicular teratocarcinomas and summarize the current state of knowledge of the TGCT microenvironment and its relationship with vascularization. Finally, we discuss the importance of vascularization as a therapeutic target for this type of malignancy.     

三维能量超声诊断子宫内膜癌的临床价值

目的比较三维能量多普勒超声测量子宫内膜良、恶性病变患者的血流参数值;研究子宫内膜癌患者病理分期与血流参数的相关性。方法选择绝经后阴道流血患者55例,测定收缩期峰值流速(PSV)、搏动指数(PI)、阻力指数(RI)及血管形成指数(VI)。结果 1子宫内膜癌组的超声血管参数PSV、PI、RI值均显著低于子宫内膜良性病变组,VI值显著高于子宫内膜良性病变组(P<0.05);2子宫内膜癌组的VI值在Ⅰ期与Ⅱ期、Ⅱ期与Ⅲ期分别比较有显著差异(P<0.05);子宫内膜癌有、无淋巴结转移组间RI和VI值差异显著(P<0.05)。结论三维能量多普勒超声技术对子宫内膜良、恶性病变的诊断与鉴别诊断有重要临床价值,为临床术前评估子宫内膜癌的分期提供了一种相对准确的新手段。