Articular cartilage of the knee is quite susceptible to injuries which are often painful and which may progress to osteoarthritis. Osteochondral autografting and allografting are currently the only treatment options which immediately restore hyaline cartilage to the injured joint. Drawbacks to these procedures such as donor site morbidity and limited tissue availability have stimulated interest in osteochondral xenografts, which have the potential advantages of low cost and abundant supply. The long-term objective of the proposed research is to develop a decellularized porcine osteochondral xenograft (OCXG) which can be available for implantation as soon as a cartilage lesion is discovered (i.e., off-the-shelf). Development includes optimization of decellularization and crosslinking methods to reduce immunogenicity and improve graft durability and integration with host tissue.
The specific Aims are as follows: 1. Compare glycosaminoglycan-containing and glycosaminoglycan-free porcine osteochondral dowels in terms of their mechanical properties and ability to support stem cell infiltration and chondroinduction in vitro. 2. Evaluate the effect of four different plant- derived, nontoxic crosslinking agents on the physical and mechanical properties of GAG(+) and GAG(-) OCXGs, as well as their effects on primary human knee chondrocyte behavior in vitro. 3. Evaluate the acute inflammatory response to GAG(+) and GAG(-) decellularized porcine OCXGs, both crosslinked and non- crosslinked using the most promising agent from SA2, in an intraarticular rabbit model. 4. Determine the capacity for crosslinked, decellularized OCXGs to repair full-thickness defects in the trochlear groove of adult dogs.
The first aim will provide important information about fundamentally different approaches to decellularization, one which seeks to preserve all extracellular matrix and one which intentionally extracts non- collagenous components (especially glycosaminoglycan) to create more porosity. Evaluations include measurement of the DNA and GAG contents, the graft cartilage's biphasic properties, and the attachment, proliferation, and matrix production of human chondrocytes cultured on the grafts.
The first aim also includes development of a novel decellularization protocol.
The second aim will reveal the potential for natural, nontoxic crosslinking agents to enhance xenograft mechanical properties and collagenase resistance. It will also determine whether chondrocytes are sensitive to the degree of crosslinking.
The third aim i nvolves short-term transplantation of OCXGs into the medial femoral condyle of mature rabbits, mainly to investigate OCXG- induced synovitis. The effects of decellularization method and crosslinking will be examined through synovial fluid analysis and histology.
The final aim will evaluate the functionality of porcine osteochondral xenografts used to fill surgically created defects in the canine knee joint. Semiquantitative scoring of macroscopic appearance and histology, in addition to indentation testing, will demonstrate whether osteochondral xengrafts are capable of restoring a healthy joint surface in this preclinical model.

Public Health Relevance

The goal of the proposed project is to develop a new treatment alternative for localized articular cartilage injuries in the knee, namely a porcine osteochondral xenograft. The project includes refinement of xenograft decellularization and crosslinking methods to reduce immunogenicity and increase durability.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Academic Research Enhancement Awards (AREA) (R15)
Project #
1R15AR066926-01A1
Application #
8879748
Study Section
Special Emphasis Panel ()
Program Officer
Wang, Fei
Project Start
2015-09-07
Project End
2018-08-31
Budget Start
2015-09-07
Budget End
2018-08-31
Support Year
1
Fiscal Year
2015
Total Cost
$366,855
Indirect Cost
$102,857
Name
Mississippi State University
Department
Engineering (All Types)
Type
Other Domestic Higher Education
DUNS #
075461814
City
Mississippi State
State
MS
Country
United States
Zip Code
39762
Elder, Steve; Chenault, Hudson; Gloth, Paul et al. (2018) Effects of antigen removal on a porcine osteochondral xenograft for articular cartilage repair. J Biomed Mater Res A 106:2251-2260
Elder, Steven; Pinheiro, Amanda; Young, Christian et al. (2017) Evaluation of genipin for stabilization of decellularized porcine cartilage. J Orthop Res 35:1949-1957
Elder, Steven; Clune, John; Walker, Jaylyn et al. (2017) Suitability of EGCG as a Means of Stabilizing a Porcine Osteochondral Xenograft. J Funct Biomater 8:
Pinheiro, Amanda; Cooley, Avery; Liao, Jun et al. (2016) Comparison of natural crosslinking agents for the stabilization of xenogenic articular cartilage. J Orthop Res 34:1037-46