Gene therapy for treatment of craniofacial dysplasia

描述（由申请人提供）：本研究的目的是开发一种新的基因治疗方案，用于颅面发育不良的围产期治疗，颅面发育不良是许多遗传疾病的主要特征，包括Apert， Crouzon, Treacher Collins， Hurler和Hunter综合征，仅举几例。临床上，他们表现为颌骨大小和形状异常，额部隆起和中脸发育不全，以及身体其他部位的骨骼异常（Hurler & Hunter）。分子生物学的最新进展使科学家能够研究许多这些疾病的病因，其中不同的基因突变导致骨生长和骨骼发育异常，导致颅面表型异常。间充质细胞主要参与骨骼的生长和发育，包括软骨细胞、骨细胞、内皮细胞和成纤维细胞，因此正常的细胞功能对骨骼的生理性生长和发育至关重要。因此，我们假设，对参与骨形成和生长的细胞有害的遗传因素可能对骨骼发育产生不利影响，最终导致颅面发育不良。根据特定的遗传异常，相关表型可以在产前、出生时（新生儿）或出生后不久（围产期）诊断，使用临床和分子方法。本研究的目的是确定通过基因治疗及时恢复突变是否可以减轻甚至预防颅面发育不良。为此，我们将采用β -己糖氨酸酶缺乏症引起的细胞功能障碍继发于骨生长异常的颅面发育不良、生长迟缓和面部畸形动物模型（hexA-/-/hexB-/-双敲除小鼠）。有趣的是，这些小鼠在出生时仅表现出轻微的表型变化，但在4-5周龄时迅速发展出异常特征。此外，他们的运动功能逐渐下降，寿命有限（1-4个月）。利用我们实验室开发的用于β -己糖氨酸酶基因治疗的伪型猫免疫缺陷病毒载体FIV(Hex)，我们将测试在hexA-/-/hexB-/-小鼠中恢复潜在的遗传缺陷是否会导致β -己糖氨酸酶活性的恢复和骨骼发育的正常化。基于我们的初步结果，我们预计我们的治疗基因在体内的成功转移和表达，导致细胞功能正常化和hexA-/-/hexB-/-表型的衰减。这项研究的完成将有助于开发新的治疗遗传疾病的方法。

DESCRIPTION (provided by applicant): The purpose of this study is the development of a novel gene therapy regime for the perinatal treatment of craniofacial dysplasia, a cardinal characteristic of many genetic disorders, including Apert, Crouzon, Treacher Collins, Hurler and Hunter syndromes, just to name a few. Clinically, they present with abnormal size and shape of the jaws, frontal bossing and midface hypoplasia, as well as skeletal anomalies in other areas of the body (Hurler & Hunter). Recent advances in molecular biology have allowed scientists to investigate the etiologic factors for many of these disorders, in which distinct genetic mutations cause abnormal bone growth and skeletal development, giving rise to abnormal craniofacial phenotype. Cells of mesenchymal origin are primarily involved in skeletal growth and development, including chondrocytes, osteocytes, endothelial cells and fibroblasts, whereby normal cellular function appears central to physiologic bone growth and development. Therefore we hypothesize that genetic factors deleterious to cells involved in bone formation and growth can adversely affect skeletal development, ultimately resulting in craniofacial dysplasia. Depending on the particular genetic anomaly, the correlate phenotype may be diagnosed prenatally, at birth (neonatally) or soon after (perinatally), using clinical as well as molecular approaches. The purpose of this study is to determine whether timely restoration of a mutation by gene therapy can attenuate or even prevent craniofacial dysplasia. For this purpose, we will employ an animal model with craniofacial dysplasia, growth retardation and facial dysmorphism secondary to abnormal bone growth due to cellular dysfunction resulting from beta-hexosaminidase deficiency (hexA-/-/hexB-/- double knockout mice). Interestingly, these mice display only mild phenotypic changes at birth, but quickly develop their aberrant features by 4-5 weeks of age. Furthermore, they have progressive decline in motor function, and limited life span (1-4 months). Utilizing a pseudotyped feline immunodeficiency viral vector developed in our laboratory for beta-hexosaminidase gene therapy, FIV(Hex), we will test whether restoration of the underlying genetic deficiency in hexA-/-/hexB-/- mice will result in restitution of beta-hexosaminidase activity and normalization of skeletal development. Based on our Preliminary Results, we anticipate successful transfer and expression of our therapeutic gene in vivo, leading to normalization of cellular function and attenuation of the hexA-/-/hexB-/- phenotype. Completion of this study will aid in the development of novel therapies for the management of genetic disorders.