Craniofacial surgery is particularly suited to tissue engineering as significant progress has been made in adipose and osseous tissue induction. With regards to soft tissue needs, craniofacial surgeons are faced with the aesthetic challenges of facial rejuvenation such as malar and lip augmentation which currently rely on the use of synthetic fillers such as hyaluronic acid and fat transfer. Similarly, reconstructive needs for soft tissue contour such as in patients suffering from Parry-Romberg syndrome and HIV related lipoatrophy are addressed with a number of treatment options. Autologous lipoinjection has become recently popularized and been shown to provide excellent outcomes, however, even in the best hands, lipotransfer does not provide a self-renewing population of cells.(2
) Thus, recent efforts by Yoshimura et al
to augment transferred adipose tissue with adipose derived stromal cells (ASCs) offer a promising application of stem cell therapy.(4
A second medical bioburden faced by craniofacial surgeons is the need for bone replacement. The craniofacial skeleton provides structural stability and mastication puts load bearing stress on several craniofacial bones. There are over 500,000 bone grafts performed annually, of which 6% are for craniofacial indications.(8
) Bone is a responsive, highly vascularized tissue that responds to local stress and strain. Bone consists of three different cell types (osteocytes, osteoblasts, and osteoclasts) which are surrounded by a matrix composed of hydroxyapatite, collagens, glycoproteins, proteoglycans and sialoproteins.(10
) With regards to the pediatric population, cleft palate represents an area where bony tissue regeneration to address the alveolar ridge and enable subsequent tooth eruption and midface development would greatly benefit from tissue engineered bone. Autogenous bone grafts, often harvested from the iliac crest have become the current gold standard to treat the alveolar cleft, however, such tissues are painful to harvest, and can be complicated by hematoma, infection and resorption.
In patients of all ages above 2 years old, a time when the calvarium can no longer regenerate on its own, calvarial defects also represent a significant reconstructive challenge. Whether from congenital malformations, trauma or cancer extirpation, the loss of bone in the craniofacial skeleton has significant structural and functional consequences. Current treatments for such skeletal defects include nonvascularized bone grafting, which are at risk of resorption, and the use of alloplastic materials which are wrought with infection, extrusion and mechanical failure. Thus, the development and clinical introduction of a biomimetic, osteoconductive scaffold would greatly benefit surgeons treating patients with osseous defects of the craniofacial skeleton.
Cancer resections and trauma can also often lead to maxillary and mandibular bony defects. Current approaches of bone grafting using nonvascularized as well as vascularized bone grafts such as those harvested from the fibula and scapula are often employed. Though vascularized grafts undergo less resorption, they often create large secondary defects and are available in a limited supply. When autologous transplantation is not possible, allogenic and xenogenic bone grafts have been employed, however, these substitutes are constrained in their osteogenicity, stability and strength.(10