Scalebar: 250?in vivoosteogenic capacity and chose not to perform anyin vitrodifferentiation prior to implantation. is osteoconductive and osteoinductive and available in large quantities and is not associated with donor site morbidity. However, allograft is not osteogenic and it carries the risk of disease transmission. The shortcomings of autografts and allografts have motivated the development of bone substitutes [1C3]. Bone substitutes consist of a scaffold, usually containing calcium or other minerals . Scaffolds can be loaded with cytokines and cells to improve osteogenesis and angiogenesis [5, 6]. Osteogenic cells (osteocytes and osteoblasts) originate from SPC that reside in the tissue OICR-0547 . MSC are a subset of SPC that are plastic-adherent in culture, can be differentiated into tissue of different lineages, and are positive for markers CD105, CD73, and CD90 and negative for CD45, CD34, CD14 or CD11b, CD79or CD19, and HLA-DR . As MSC can undergo differentiation into tissues unrelated to the tissue in which they originally reside, MSC from one tissue may be useful in another, and MSC for bone substitutes need not to originate from bone and could potentially be harvested from adipose tissue [7, 9]. In contrast to bone marrow, adipose tissue is easier to retrieve and can often be harvested in abundant quantities, A-CEAC show lower levels of senescence and can be expanded to higher passagesin vitrocompared to BM-CEAC [10C12]. This makes adipose tissue an appealing alternative to bone marrow as a source of SPC for bone substitutes, provided that A-CEAC have osteogenic capacity similar to or better than BM-CEAC. Many studies investigate different scaffolds for A-CEAC; however, the number of studies comparing A-CEAC to BM-CEAC with respect toin vivobone formation capacity is very low and varies in species, cells used, characterization method, scaffold, model, and quantitative assessment, thus making direct comparison difficult [13, 14]. BM-CEAC are currently used in clinical settings . The sheep is a frequently used model for orthopaedic research for several reasons: the bone size is large enough to perform complex orthopaedic procedures and for testing medical devices and biomaterials; the lifespan is short enough to perform age-related studies in diseases OICR-0547 such as osteoarthritis and osteoporosis ; and their bone remodelling is comparable to that of humans . Very little is known about A-CEAC for BTE. To our knowledge, only one study has compared ovine A-CEAC to BM-CEAC with respect toin vivobone formation; furthermore, the comparison was OICR-0547 OICR-0547 performed in an orthotopic environment . Ovine A-CEAC and BM-CEAC have not yet been compared regarding ectopic bone formation to assess the intrinsic osteogenic capacity, so this would bring new information about ovine A-CEAC. This study aimed to investigate A-CEAC osteogenesis using BM-CEAC osteogenesis as baseline. The objectives of this study were to use a subcutaneous immunodeficient mouse model  to (1) assess the efficacy of A-CEAC on bone formation, (2) compare bone formation between ovine A-CEAC and BM-CEAC, and (3) compare bone formation between different doses of A-CEAC to see if seeding A-CEAC closer improves osteogenesis. Furthermore, we investigate whether a marker for human vimentin (HVIM) can be used to identify ovine cells in implants and thus to reveal the origin of the cells. We hypothesize that A-CEAC can form new bone in this model, that A-CEAC can form new bone at Rabbit polyclonal to FBXO42 the same BV/TV as BM-CEAC, that seeding A-CEAC closer improves osteogenesis, and that HVIM can be used to identify sheep cells in histomorphometry. 2. Materials and Methods 2.1. Study Design A-CEAC and BM-CEAC were isolated from ovine adipose tissue or iliac crest aspirate, culture expanded, and seeded on hydroxyapatite (HA) granules. Mice were divided into two groups. In mouse group 1, granules seeded with 0.5 106 BM-CEAC (denoted BM-CEAC) were implanted in the left pouches, and granules seeded with 0.5 106 A-CEAC (denoted A-CEAC1) were implanted in the right pouches. In mouse group 2, granules were seeded with 1.0 106 A-CEAC (denoted A-CEAC2) for the left pouches and 1.5 106 A-CEAC (denoted A-CEAC3) for the right pouches. Mice and implant groups are shown in Table 1. The workflow is outlined in Figure 1. Open in a separate window Figure 1 Study design. CEAC from adipose tissue (A-CEAC) and bone marrow (BM-CEAC) was isolated from 5 female sheep, expandedin vitro,and seeded onto HA prior to subcutaneous implantation in immunodeficient mice. After 8 weeks, implants were harvested and bone volume versus total tissue volume was assessed by histomorphometry. Each mouse received four implants as previously described . Table 1 Animal and implant groups. OICR-0547 Cells were seeded on 40?mg HA scaffold as.