Development of Bone and Cartilage in Tissue-Engineered Human Middle Phalanx Models

Abstract

Human middle phalanges were tissue-engineered with midshaft scaffolds of poly(L-lactide-epsilon-caprolactone) [P(LA-CL)], hydroxyapatite-P(LA-CL), or beta-tricalcium phosphate-P(LA-CL) and end plate scaffolds of bovine chondrocyte-seeded polyglycolic acid. Midshafts were either wrapped with bovine periosteum or left uncovered. Constructs implanted in nude mice for up to 20 weeks were examined for cartilage and bone development as well as gene expression and protein secretion, which are important in extracellular matrix (ECM) formation and mineralization. Harvested 10- and 20-week constructs without periosteum maintained end plate cartilage but no growth plate formation. They also consisted of chondrocytes secreting type II collagen and proteoglycan, and they were composed of midshaft regions devoid of bone. In all periosteum-wrapped constructs at like times, end plate scaffolds held chondrocytes elaborating type II collagen and proteoglycan and cartilage growth plates resembling normal tissue. Chondrocyte gene expression of type II collagen, aggrecan, and bone sialoprotein varied depending on midshaft composition, presence of periosteum, and length of implantation time. Periosteum produced additional cells, ECM, and mineral formation within the different midshaft scaffolds. Periosteum thus induces midshaft development and mediates chondrocyte gene expression and growth plate formation in cartilage regions of phalanges. This work is important for understanding developmental principles of tissue-engineered phalanges and by extension those of normal growth plate cartilage and bone.

The Nature and Role of Periosteum in Bone and Cartilage Regeneration

“…Cranial periosteum was consistently obtained from the frontal region of calf skulls as opposed to potentially different periosteum from other regions. The periosteum/scaffold constructs and counterpart controls were then incubated (37 ° C, 5% CO 2 ) for ϳ 1 week in separate petri dishes containing M199 medium supplemented with 10% fetal bovine serum and 1% antibiotic/antimycotic [Wada et al, 2009]. After incubation, constructs and controls were implanted in the dorsal subcutaneous space of 4-to 6-week-old male athymic (nu/nu) mice (Harlan Laboratories, Indianapolis, Ind., USA) for 10 and 20 weeks [Isogai et al, 1999[Isogai et al, , 2006Landis et al, 2005;Wada et al, 2009].…”

“…Half of each specimen was fixed in 10% neutral buffered formalin for 24 h, examined and documented by X-ray radiography [Wada et al, 2009], and then dehydrated in graded ethanols, embedded in paraffin, and processed for histological study. Samples were cut on a microtome into 5-m-thick sections and then stained in various solutions.…”

“…The remaining half of each retrieved construct was immersed in RNA later (Ambion/Life Technologies, Carlsbad, Calif., USA), frozen in liquid nitrogen, and stored at -80 ° C for subsequent QRT-PCR analysis Wada et al, 2009]. The genes examined were related to bovine bone and cartilage formation and mineralization and included type I collagen, type II collagen, runx2, and bone sialoprotein (BSP).…”

Coefficient of Friction Patterns Can Identify Damage in Native and Engineered Cartilage Subjected to Frictional-Shear Stress

“…17,26 Various methodologies exist for producing EC, yet the mechanical properties of EC generated in vitro are consistently inferior to those of native cartilage (NC). 7,12,28 Thus, mechanical testing plays an important role in cartilage tissue engineering, both in characterizing EC constructs, and in directing work for the improvement of EC constructs.…”

BMP2 promotes chondrocyte proliferation via the Wnt/β-catenin signaling pathway

“…Cartilage is composed of chondroctyes that produce a large amount of extracellular matrix (ECM), including type II collagen and proteoglycan (PG) (3). Chondroctyes rapidly respond to changes in the articular microenvironment and regulate the dynamic equilibrium between the degradation and synthesis of the ECM, which is crucial to the maintenance of cartilage function (4,5). Therefore, the functional changes of chondrocytes contribute to the degradation of the articular cartilage, and thus to the pathologenesis of OA.…”