CELL - BASED NANOCOMPOSITES AND BIOMOLECULES FOR BONE TISSUE ENGINEERING - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 566

This observation could be attributed to the fact that the MSCs may be circu-
lating in the prenatal organism and residing in tissues of the adult 153 . UCB showed
the lowest colony frequency and contrary to adipose tissue with the highest
colony frequency 149 . MSCs from UCB showed the longest culture period and the
highest proliferation ability; MSCs from bone marrow had the shortest culture
period and lowest proliferation ability. Another noteworthy point to be elabo-
rated upon was that MSCs from UCB did not show adipogenic differentiation
capacity, unlike those MSCs from bone marrow and adipose tissue, which showed
osteogenic, chondrogenic, and adipogenic differentiation 149 . With regards to this,
it is debated that a hierarchical or restricted differentiation capability of MSCs
may be possible 17,154 . The proliferation rates of bone marrow, adipose and perios-
teum were similar after four, seven and eleven days of culture in a separate study.
Osteogenic and chondrogenic differentiation were achieved in all the MSCs.
Using a rabbit model, the authors demonstrated that bone-marrow and perios-
teum-derived MSCs had superior physeal arrest over adipose-derived MSCs 150 .
For the comparative studies between bone marrow, adipose tissue, synovium,
periosteum and skeletal muscle, bone marrow samples generated the greatest
extent of calcifi cation, followed by synovium, periosteum, adipose and muscle
samples. For bone marrow samples, the colony number for every 10 3 nucleated
cells was lower and cell number per colony was greater as compared to other
tissue sources. The number of nucleated cells ( × 10 3 ) per volume or weight of

tissue obtained was as follows: bone marrow (2045 ± 920), adipose tissue (22 ± 21),

synovium (3 1). Similarity in epitope

profi les were found regardless of the tissue source 152 . A study also conducted on
the immunological properties of bone marrow stromal cells and adipose tissue
derived MSCs and concluded that their properties were maintained during pre-
and post-osteogenic induction in vitro and seemed to be similar in both tissues 155 .

± 4), periosteum (3 ± 6) and muscle (2 ±

16.5 CURRENT PERSPECTIVE

Advanced technologies are required in order to develop a hierarchical-
assembled bone-like composite over several length scales for bone tissue applica-
tions. Room temperature fabrication techniques need further honing as
biomimetic materials usually contain cells, proteins, growth factors and the like,
and operating temperature is pivotal in their survival and integrity of the osteo-
blastic processes. The interplay between proteins, cells and materials renders
further probing and understanding, so that these nuggets of knowledge can be
translated into modulating biological pathways that are favorable for bone regen-
eration. Other critical issues involves maintaining suffi cient material construct
in vivo before osteogenesis can successfully take place, adequate material proper-
ties—especially in load-bearing sites—desirable material surface properties for
the attraction of cells at the material-graft interface, amenability to contouring
for implantation in different sizes and shapes of bony defects. Lastly, the graft has
to support angiogenesis and vascularization for healing and bone remodeling.