Functional tissue engineering of articular cartilage for biological joint resurfacing-The 2021 Elizabeth Winston Lanier Kappa Delta Award.

Biological resurfacing of entire articular surfaces represents a challenging strategy for the treatment of cartilage degeneration that occurs in osteoarthritis. Not only does this approach require anatomically sized and functional engineered cartilage, but the inflammatory environment within an arthritic joint may also inhibit chondrogenesis and induce degradation of native and engineered cartilage. Here, we present the culmination of multiple avenues of interdisciplinary research leading to the development and testing of bioartificial cartilage for tissue-engineered resurfacing of the hip joint.

Biological resurfacing in a canine model of hip osteoarthritis.

Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissue-engineered, bicomponent implant to restore hip function in a canine hip osteoarthritis model. This resorbable implant was specifically designed to function mechanically from the time of repair and to biologically integrate with native tissues for long-term restoration.

Chondrogenic, hypertrophic, and osteochondral differentiation of human mesenchymal stem cells on three-dimensionally woven scaffolds.

The development of mechanically functional cartilage and bone tissue constructs of clinically relevant size, as well as their integration with native tissues, remains an important challenge for regenerative medicine. The objective of this study was to assess adult human mesenchymal stem cells (MSCs) in large, three-dimensionally woven poly(ε-caprolactone; PCL) scaffolds in proximity to viable bone, both in a nude rat subcutaneous pouch model and under simulated conditions in vitro. In Study I, various scaffold permutations-PCL alone, PCL-bone, "point-of-care" seeded MSC-PCL-bone, and chondrogenically precultured Ch-MSC-PCL-bone constructs-were implanted in a dorsal, ectopic pouch in a nude rat.

Composite Cellularized Structures Created from an Interpenetrating Polymer Network Hydrogel Reinforced by a 3D Woven Scaffold.

Biomaterial scaffolds play multiple roles in cartilage tissue engineering, including controlling architecture of newly formed tissue while facilitating growth of embedded cells and simultaneously providing functional properties to withstand the mechanical environment within the native joint. In particular, hydrogels-with high water content and desirable transport properties-while highly conducive to chondrogenesis, often lack functional mechanical properties. In this regard, interpenetrating polymer network (IPN) hydrogels can provide mechanical toughness greatly exceeding that of individual components; however, many IPN materials are not biocompatible for cell encapsulation.

Chondrogenic Differentiation Processes in Human Bone-Marrow Aspirates Seeded in Three-Dimensional-Woven Poly(ɛ-Caprolactone) Scaffolds Enhanced by Recombinant Adeno-Associated Virus-Mediated SOX9 Gene Transfer.

Combining gene therapy approaches with tissue engineering procedures is an active area of translational research for the effective treatment of articular cartilage lesions, especially to target chondrogenic progenitor cells such as those derived from the bone marrow. This study evaluated the effect of genetically modifying concentrated human mesenchymal stem cells from bone marrow to induce chondrogenesis by recombinant adeno-associated virus (rAAV) vector gene transfer of the sex-determining region Y-type high-mobility group box 9 (SOX9) factor upon seeding in three-dimensional-woven poly(ɛ-caprolactone; PCL) scaffolds that provide mechanical properties mimicking those of native articular cartilage. Prolonged, effective SOX9 expression was reported in the constructs for at least 21 days, the longest time point evaluated, leading to enhanced metabolic and chondrogenic activities relative to the control conditions (reporter lacZ gene transfer or absence of vector treatment) but without affecting the proliferative activities in the samples.

Comparison of Fixation Techniques of 3D-Woven Poly(ϵ-Caprolactone) Scaffolds for Cartilage Repair in a Weightbearing Porcine Large Animal Model.

Objective To test different fixation methods of a 3-dimensionally woven poly(ϵ-caprolactone) (PCL) scaffold within chondral defects of a weightbearing large animal model. Methods Full thickness chondral defects were made in the femoral condyles of 15 adult male Yucatan mini-pigs. Two surgical approaches were compared including total arthrotomy (traditional) and a retinaculum-sparing, minimally invasive surgery (MIS) approach.

Functional outcome measures in a surgical model of hip osteoarthritis in dogs.

Background: The hip is one of the most common sites of osteoarthritis in the body, second only to the knee in prevalence. However, current animal models of hip osteoarthritis have not been assessed using many of the functional outcome measures used in orthopaedics, a characteristic that could increase their utility in the evaluation of therapeutic interventions. The canine hip shares similarities with the human hip, and functional outcome measures are well documented in veterinary medicine, providing a baseline for pre-clinical evaluation of therapeutic strategies for the treatment of hip osteoarthritis.

Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing.

Biological resurfacing of entire articular surfaces represents an important but challenging strategy for treatment of cartilage degeneration that occurs in osteoarthritis. Not only does this approach require anatomically sized and functional engineered cartilage, but the inflammatory environment within an arthritic joint may also inhibit chondrogenesis and induce degradation of native and engineered cartilage. The goal of this study was to use adult stem cells to engineer anatomically shaped, functional cartilage constructs capable of tunable and inducible expression of antiinflammatory molecules, specifically IL-1 receptor antagonist (IL-1Ra).

Composite three-dimensional woven scaffolds with interpenetrating network hydrogels to create functional synthetic articular cartilage.

The development of synthetic biomaterials that possess mechanical properties that mimic those of native tissues remains an important challenge to the field of materials. In particular, articular cartilage is a complex nonlinear, viscoelastic, and anisotropic material that exhibits a very low coefficient of friction, allowing it to withstand millions of cycles of joint loading over decades of wear. Here we show that a three-dimensionally woven fiber scaffold that is infiltrated with an interpenetrating network hydrogel can provide a functional biomaterial that provides the load-bearing and tribological properties of native cartilage.

Genipin-crosslinked cartilage-derived matrix as a scaffold for human adipose-derived stem cell chondrogenesis.

Autologous cell-based tissue engineering using three-dimensional scaffolds holds much promise for the repair of cartilage defects. Previously, we reported on the development of a porous scaffold derived solely from native articular cartilage, which can induce human adipose-derived stem cells (ASCs) to differentiate into a chondrogenic phenotype without exogenous growth factors. However, this ASC-seeded cartilage-derived matrix (CDM) contracts over time in culture, which may limit certain clinical applications.

The inhibition by interleukin 1 of MSC chondrogenesis and the development of biomechanical properties in biomimetic 3D woven PCL scaffolds.

Tissue-engineered constructs designed to treat large cartilage defects or osteoarthritic lesions may be exposed to significant mechanical loading as well as an inflammatory environment upon implantation in an injured or diseased joint. We hypothesized that a three-dimensionally (3D) woven poly(ε-caprolactone) (PCL) scaffold seeded with bone marrow-derived mesenchymal stem cells (MSCs) would provide biomimetic mechanical properties in early stages of in vitro culture as the MSCs assembled a functional, cartilaginous extracellular matrix (ECM). We also hypothesized that these properties would be maintained even in the presence of the pro-inflammatory cytokine interleukin-1 (IL-1), which is found at high levels in injured or diseased joints.

Engineered cartilage using primary chondrocytes cultured in a porous cartilage-derived matrix.

Aim: To investigate the cell growth, matrix accumulation and mechanical properties of neocartilage formed by human or porcine articular chondrocytes on a porous, porcine cartilage-derived matrix (CDM) for use in cartilage tissue engineering.

Materials & Methods: We examined the physical properties, cell infiltration and matrix accumulation in different formulations of CDM and selected a CDM made of homogenized cartilage slurry as an appropriate scaffold for long-term culture of human and porcine articular chondrocytes.

Results: The CDM scaffold supported growth and proliferation of both human and porcine chondrocytes.

Three-dimensional culture systems to induce chondrogenesis of adipose-derived stem cells.

Stem cells can easily be harvested from adipose tissue in large numbers for use in tissue-engineering approaches for cartilage repair or regeneration. In this chapter, we describe in vitro tissue-engineering models that we have used in our laboratory for the chondrogenic induction of adipose-derived stem cells (ASC). In addition to the proper growth factor environment, chondrogenesis requires cells to be maintained in a rounded morphology in three-dimensional (3D) culture, and thus properties of the biomaterial scaffold also play a critical role in ASC differentiation.

Multifunctional hybrid three-dimensionally woven scaffolds for cartilage tissue engineering.

The successful replacement of large-scale cartilage defects or osteoarthritic lesions using tissue-engineering approaches will likely require composite biomaterial scaffolds that have biomimetic mechanical properties and can provide cell-instructive cues to control the growth and differentiation of embedded stem or progenitor cells. This study describes a novel method of constructing multifunctional scaffolds for cartilage tissue engineering that can provide both mechanical support and biological stimulation to seeded progenitor cells. 3-D woven PCL scaffolds were infiltrated with a slurry of homogenized CDM of porcine origin, seeded with human ASCs, and cultured for up to 42 d under standard growth conditions.

2010 Nicolas Andry Award: Multipotent adult stem cells from adipose tissue for musculoskeletal tissue engineering.

Background: Cell-based therapies such as tissue engineering provide promising therapeutic possibilities to enhance the repair or regeneration of damaged or diseased tissues but are dependent on the availability and controlled manipulation of appropriate cell sources.

Questions/purposes: The goal of this study was to test the hypothesis that adult subcutaneous fat contains stem cells with multilineage potential and to determine the influence of specific soluble mediators and biomaterial scaffolds on their differentiation into musculoskeletal phenotypes.

Methods: We reviewed recent studies showing the stem-like characteristics and multipotency of adipose-derived stem cells (ASCs), and their potential application in cell-based therapies in orthopaedics.

Isolation of adipose-derived stem cells and their induction to a chondrogenic phenotype.

The ability to isolate, expand and differentiate adult stem cells into a chondrogenic lineage is an important step in the development of tissue engineering approaches for cartilage repair or regeneration for the treatment of joint injury or osteoarthritis, as well as for their application in plastic or reconstructive surgery. Adipose-derived stem cells (ASCs) provide an abundant and easily accessible source of adult stem cells for use in such regenerative approaches. This protocol first describes the isolation of ASCs from liposuction aspirate.

The effects of BMP6 overexpression on adipose stem cell chondrogenesis: Interactions with dexamethasone and exogenous growth factors.

Adipose-derived stem cells (ASCs) are multipotent progenitors that can be chondrogenically induced by growth factors such as bone morphogenetic protein 6 (BMP-6). We hypothesized that nonviral transfection of a BMP-6 construct (pcDNA3-BMP6) would induce chondrogenic differentiation of ASCs encapsulated in alginate beads and that differentiation would be enhanced by the presence of the synthetic glucocorticoid dexamethasone (DEX) or the combination of epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2), and transforming growth factor beta-1 (TGF-beta1), collectively termed expansion factors (EFs). Chondrogenesis was assessed using quantitative real-time polymerase chain reaction for types I, II, and X collagen, aggrecan, and BMP6.

Control of stem cell fate by physical interactions with the extracellular matrix.

A diverse array of environmental factors contributes to the overall control of stem cell activity. In particular, new data continue to mount on the influence of the extracellular matrix (ECM) on stem cell fate through physical interactions with cells, such as the control of cell geometry, ECM geometry/topography at the nanoscale, ECM mechanical properties, and the transmission of mechanical or other biophysical factors to the cell. Here, we review some of the physical processes by which cues from the ECM can influence stem cell fate, with particular relevance to the use of stem cells in tissue engineering and regenerative medicine.

What standards can (and can't) tell us about a spinal device.

Standards are important tools in evaluating and predicting the performance of medical devices prior to implantation. There are three types of standards that are available: a material specification, a standard test method, and a standard test guide. Each of these types of standards is defined with examples of how each is used to facilitate evaluation of medical devices.

Chondrogenic differentiation of adipose-derived adult stem cells by a porous scaffold derived from native articular cartilage extracellular matrix.

Adipose-derived adult stem cells (ASCs) have the ability to differentiate into a chondrogenic phenotype in response to specific environmental signals such as growth factors or artificial biomaterial scaffolds. In this study, we examined the hypothesis that a porous scaffold derived exclusively from articular cartilage can induce chondrogenesis of ASCs. Human ASCs were seeded on porous scaffolds derived from adult porcine articular cartilage and cultured in standard medium without exogenous growth factors.

Differentiation of adipose stem cells.

The broad definition of a stem cell is a cell that has the ability to self-renew and differentiate into one or more specialized terminally differentiated cell types. It has become evident that stem cells persist in, and can be isolated from, many adult tissues. Adipose tissue has been shown to contain a population of cells that retain a high proliferation capacity in vitro and the ability to undergo extensive differentiation into multiple cell lineages.

Monolayer cell expansion conditions affect the chondrogenic potential of adipose-derived stem cells.

Adipose-derived stem cells (ASCs) are an abundant, readily available population of multipotent progenitor cells that reside in adipose tissue. Isolated ASCs are typically expanded in monolayer on standard tissue culture plastic with a basal medium containing 10% fetal bovine serum. However, recent data suggest that altering the monolayer expansion conditions by using suspension culture plastic, adding growth factors to the medium, or adjusting the seeding density may affect the self-renewal rate, multipotency, and lineage-specific differentiation potential of the ASCs.

Extended passaging, but not aldehyde dehydrogenase activity, increases the chondrogenic potential of human adipose-derived adult stem cells.

Adipose-derived adult stem (ADAS) cells represent an abundant population of multipotent mesodermal cells residing in various adipose tissue depots. ADAS cell preparations appear heterogeneous, yet at a clonal level, greater than 50% of these cells exhibit multilineage differentiation potential. To date, there have been few attempts to define prospectively a homogenous population of multipotent cells.

Potent induction of chondrocytic differentiation of human adipose-derived adult stem cells by bone morphogenetic protein 6.

Objective: Recent studies have identified an abundant source of multipotent progenitor cells in subcutaneous human adipose tissue, termed human adipose-derived adult stem cells (ADAS cells). In response to specific media formulations, including transforming growth factor beta1 (TGFbeta1), these cells exhibit significant ability to differentiate into a chondrocyte-like phenotype, expressing cartilage-specific genes and proteins such as aggrecan and type II collagen. However, the influence of other growth factors on the chondrogenic differentiation of ADAS cells is not fully understood.

Polyetheretherketone as a biomaterial for spinal applications.

Threaded lumbar interbody spinal fusion devices (TIBFD) made from titanium have been reported to be 90% effective for single-level lumbar interbody fusion, although radiographic determination of fusion has been intensely debated in the literature. Using blinded radiographic, biomechanic, histologic, and statistical measures, we evaluated a radiolucent polyetheretherketone (PEEK)-threaded interbody fusion device packed with autograft or rhBMP-2 on an absorbable collagen sponge in 13 sheep at 6 months. Radiographic fusion, increased spinal level biomechanical stiffness, and histologic fusion were demonstrated for the PEEK cages filled with autograft or rhBMP-2 on a collagen sponge.