Repairing critical-sized rat calvarial defects with a periosteal cell-seeded small intestinal submucosal layer

The periosteum: a simple tissue with many faces, with special reference to the antler-lineage periostea

Periosteum is a thin membrane covering bone surfaces and consists of two layers: outer fibrous layer and inner cambium layer. Simple appearance of periosteum has belied its own complexity as a composite structure for physical bone protection, mechano-sensor for sensing mechanical loading, reservoir of biochemical molecules for initiating cascade signaling, niche of osteogenic cells for bone formation and repair, and "umbilical cord" for nourishing bone tissue. Periosteum-derived cells (PDCs) have stem cell attributes: self-renewal (no signs of senescence until 80 population doublings) and multipotency (differentiate into fibroblasts, osteoblasts, chondrocytes, adipocytes and skeletal myocytes). In this review, we summarized the currently available knowledge about periosteum and with special references to antler-lineage periostea, and demonstrated that although periosteum is a type of simple tissue in appearance, with multiple faces in functions; antler-lineage periostea add another dimension to the properties of somatic periostea: capable of initiation of ectopic organ formation upon transplantation and full mammalian organ regeneration when interacted with the covering skin. Very recently, we have translated this finding into other mammals, i.e. successfully induced partial regeneration of the amputated rat legs. We believe further refinement along this line would greatly benefit human health.

Effects of the combination of low-level laser therapy and anionic polymer membranes on bone repair

In view of the limitations of bone reconstruction surgeries using autologous grafts as a gold standard, tissue engineering is emerging as an alternative, which permits the fabrication and improvement of scaffolds to stimulate osteogenesis and angiogenesis, processes that are essential for bone repair. Polymers are used to mimic the extracellular bone matrix and support cell growth. In addition, bone neoformation can be induced by external factors such as laser irradiation, which stimulates bone metabolism. The objective of this study was to evaluate the regeneration of bone defects using collagen and elastin membranes derived from intestinal serosa and bovine auricular cartilage combined with low-level laser application. Thirty-six Wistar rats were operated to create a 3-mm defect in the distal metaphysis of the left femur and divided into six groups: G1 (control, no treatment); G2 (laser); G3 (elastin graft), G4 (elastin+laser); G5 (collagen graft); G6 (collagen+laser). The animals were sacrificed 6 weeks after surgery and the femurs were removed for analysis of bone repair. Macroscopic and radiological results showed the absence of an infectious process in the surgical area. This was confirmed by histological analysis, which revealed no inflammatory infiltrate. Histomorphometry showed that the formation of new bone started from the margins of the bone defect and its volume was greater in elastin+laser and collagen+laser. We conclude that newly formed bone in the graft area was higher in the groups that received the biomaterials and laser. The collagen and elastin matrices showed biocompatibility.

Use of an anionic collagen matrix made from bovine intestinal serosa for in vivo repair of cranial defects

Polymeric biomaterials composed of extracellular matrix components possess osteoconductive capacity that is essential for bone healing. The presence of collagen and the ability to undergo physicochemical modifications render these materials a suitable alternative in bone regenerative therapies. The objective of this study was to evaluate the osteogenic capacity of collagen-based matrices (native and anionic after alkaline hydrolysis) made from bovine intestinal serosa (MBIS). Twenty-five animals underwent surgery to create a cranial defect to be filled with native and anionic collagen matrixes, mmineralized and non mineralized. The animals were killed painlessly 6 weeks after surgery and samples of the wound area were submitted to routine histology and morphometric analysis. In the surgical area there was new bone formation projecting from the margins to the center of the defect. More marked bone neoformation occurred in the anionic matrices groups in such a way that permitted union of the opposite margins of the bone defect. The newly formed bone matrix exhibited good optical density of type I collagen fibers. Immunoexpression of osteocalcin by osteocytes was observed in the newly formed bone. Morphometric analysis showed a greater bone volume in the groups receiving the anionic matrices compared to the native membranes. Mineralization of the biomaterial did not increase its osteoregenerative capacity. In conclusion, the anionic matrix exhibits osteoregenerative capacity and is suitable for bone reconstruction therapies.

Preparation and characterization of acellular adipose tissue matrix using a combination of physical and chemical treatments

Decellularized adipose extracellular matrix (ECM) has been used in the clinic to support the regeneration of adipose tissues. The methods used to produce adipose tissue ECM scaffolds exhibit distinct effects upon the structural and functional components of the resultant scaffold material. The current study presents an acellular ECM scaffold from human adipose tissues derived using successive physical and chemical treatments, including repeated freeze-thaw cycles followed by centrifugation, polar solvent extraction and enzymatic digestion. Cellular components, including nucleic acids were effectively removed without significant disruption of the morphology or structure of the ECM. The compositions of major ECM components were evaluated, including acid/pepsin soluble collagen, sulfated glycosaminoglycan and laminin. The decellularized ECM exhibited satisfactory mechanical properties. Cell seeding experiments involving human adipose-derived stem cells indicated that the decellularized ECM provided an inductive microenvironment for adipogenesis without the need for exogenous differentiation factors. Higher levels of glycerol-3-phosphate dehydrogenase activity were observed among induced cells in the ECM scaffolds when compared with induced cells in collagen type I scaffolds. In conclusion, the results suggested that the decellularized ECM, containing biological and chemical cues of native human ECM, may be an ideal scaffold material for autologous and allograft tissue engineering.

Evaluation of Amniotic Multipotential Tissue Matrix to Augment Healing of Demineralized Bone Matrix in an Animal Calvarial Model

Amniotic multipotential tissue matrix (AmnioMTM) is a membrane material derived from placental tissues and rich in growth factors that have been reported to have potential in healing bone. This study hypothesized that demineralized bone matrix (DBM) supplemented with AmnioMTM would accelerate healing and bone formation as compared with DBM alone in a critical size (10 mm) rat calvarial bone defect model. Five DBM grafts and 5 DBM supplemented with AmnioMTM grafts were implanted in a 10-mm critical sized defect in 10 rats (1 implant per rat). After 4 weeks, animals were euthanized and defects evaluated by microCT and histology. There were no statistical differences in microCT data for mineral density, percent bone fill, or bone surface to volume ratios between groups, though the bone surface to volume ratio for the amnio-supplemented group suggested increased osteoid activity as compared with the DBM alone group. Histological data also indicated active osteoid activity and induced bone formation in the center of defects implanted with AmnioMTM supplemented graft as compared with DBM graft alone suggesting some potential osteoinductive potential. However, there was no significant difference at the mean percent of newly mineralized bone in the DBM group defect as compared with the AmnioMTM supplemented graft material. These data suggest that while bone formation was not increased at this early time point, the increased osteoid activity and the induction of new bone in the middle of the defect by the AmnioMTM indicates that further study is needed to assess its potential benefit to bone healing and regeneration.

Comparison of bone dust with other types of bone grafts for cranioplasty

PURPOSE

Split calvarial bone graft is preferred in the reconstruction of calvarial defects. However, it is not feasible for use in some challenging cases and in children. Particulate bone graft containing viable osteoblasts could be an attractive alternative.

MATERIALS AND METHODS

A total of 32 female rats were randomly separated into 4 groups. Full-thickness bone graft from rat calvaria was harvested in diameters of 8 × 8 mm. In group 1, the periosteum and skin were closed without any bone graft; bone dust particles were placed in group 2; bone fragments were placed in group 3; and full-thickness cranial bone graft was placed in group 4. After 12 weeks, all rats were killed. Degrees of resorption, foreign body reaction, and bone spicule length were assessed histologically, and an immunohistochemical study was used to show bone graft viability.

RESULTS

In graft viability, osteogenesis, and osteoblastic differentiation, groups 3 and 4 were similar and superior to groups 1 and 2. No osteoblastic activity and no viable bone dust were detected in groups 1 and 2. Resorption was observed in every preparate that contains bone tissue, and foreign body reaction was prominent in small bone groups, such as in group 2.

CONCLUSIONS

In the full-thickness cranial bone graft group and the bone fragment group, the preservation of bone viability was obviously superior to the bone dust group and the periosteum-only group. In conclusion, bone dust behaved like the periosteum and could not create new bone, whereas bone particles behaved like the full-thickness cranial bone graft and were capable of preserving viability.

Comparison of in vivo adipogenic capabilities of two different extracellular matrix microparticle scaffolds

BACKGROUND

The extracellular matrix is an essential microenvironment for cell survival activity. The adipose tissue extract microparticle scaffolds from human adipose tissue and small intestine submucosa microparticle scaffolds from porcine jejunum were prepared. Their effects on the adipogenic capabilities of human adipose-derived stem cells were compared in vivo.

METHODS

A combination of physical and chemical methods was used to decellularize human fat and porcine jejunum. Expression of CD molecules on the adipose-derived stem cell surface was determined by flow cytometry. The stem cells were then cultured with the scaffold materials in vitro. The cell-scaffold complexes were implanted subcutaneously into nude mice, and samples were collected 4 and 8 weeks later. The adipogenic differentiation capabilities of adipose-derived stem cells were studied by histologic methods and real-time polymerase chain reaction.

RESULTS

The authors observed high expression of CD90 and CD44; no expression of CD34, CD45, CD31, or CD106; and weak positive expression of CD49d on the extracted cells, which indicates that the cells were adipose-derived stem cells. The main constituent of the decellularized adipose tissue extract and small intestine submucosa microparticles was collagenous fiber, and the cells proliferated faster on the adipose tissue extract than on small intestine submucosa. Formation of adipocytes in the adipose tissue extract group was closer to that of normal human fat tissue compared with that of the small intestine submucosa group.

CONCLUSIONS

Extracellular matrix microparticle scaffolds could promote proliferation, adhesion, and adipogenic differentiation of adipose-derived stem cells. The role of the adipose tissue extract microparticle scaffold in promoting adipogenesis was stronger and more suitable as a vector in fatty tissue engineering.

Elucidating multiscale periosteal mechanobiology: a key to unlocking the smart properties and regenerative capacity of the periosteum?

The periosteum, a thin, fibrous tissue layer covering most bones, resides in a dynamic, mechanically loaded environment. The periosteum also provides a niche for mesenchymal stem cells. The mechanics of periosteum vary greatly between species and anatomical locations, indicating the specialized role of periosteum as bone's bounding membrane. Furthermore, periosteum exhibits stress-state-dependent mechanical and material properties, hallmarks of a smart material. This review discusses what is known about the multiscale mechanical and material properties of the periosteum as well as their potential effect on the mechanosensitive progenitor cells within the tissue. Furthermore, this review addresses open questions and barriers to understanding periosteum's multiscale structure-function relationships. Knowledge of the smart material properties of the periosteum will maximize the translation of periosteum and substitute periosteum to regenerative medicine, facilitate the development of biomimetic tissue-engineered periosteum for use in instances where the native periosteum is lacking or damaged, and provide inspiration for a new class of smart, advanced materials.

Elucidating multiscale periosteal mechanobiology: a key to unlocking the smart properties and regenerative capacity of the periosteum?

The periosteum, a thin, fibrous tissue layer covering most bones, resides in a dynamic, mechanically loaded environment. The periosteum also provides a niche for mesenchymal stem cells. The mechanics of periosteum vary greatly between species and anatomical locations, indicating the specialized role of periosteum as bone's bounding membrane. Furthermore, periosteum exhibits stress-state-dependent mechanical and material properties, hallmarks of a smart material. This review discusses what is known about the multiscale mechanical and material properties of the periosteum as well as their potential effect on the mechanosensitive progenitor cells within the tissue. Furthermore, this review addresses open questions and barriers to understanding periosteum's multiscale structure-function relationships. Knowledge of the smart material properties of the periosteum will maximize the translation of periosteum and substitute periosteum to regenerative medicine, facilitate the development of biomimetic tissue-engineered periosteum for use in instances where the native periosteum is lacking or damaged, and provide inspiration for a new class of smart, advanced materials.

Concise review: the periosteum: tapping into a reservoir of clinically useful progenitor cells

Elucidation of the periosteum and its regenerative potential has become a hot topic in orthopedics. Yet few review articles address the unique features of periosteum-derived cells, particularly in light of translational therapies and engineering solutions inspired by the periosteum's remarkable regenerative capacity. This review strives to define periosteum-derived cells in light of cumulative research in the field; in addition, it addresses clinical translation of current insights, hurdles to advancement, and open questions in the field. First, we examine the periosteal niche and its inhabitant cells and the key characteristics of these cells in the context of mesenchymal stem cells and their relevance for clinical translation. We compare periosteum-derived cells with those derived from the marrow niche in in vivo studies, addressing commonalities as well as features unique to periosteum cells that make them potentially ideal candidates for clinical application. Thereafter, we review the differentiation and tissue-building properties of periosteum cells in vitro, evaluating their efficacy in comparison with marrow-derived cells. Finally, we address a new concept of banking periosteum and periosteum-derived cells as a novel alternative to currently available autogenic umbilical blood and perinatal tissue sources of stem cells for today's population of aging adults who were "born too early" to bank their own perinatal tissues. Elucidating similarities and differences inherent to multipotent cells from distinct tissue niches and their differentiation and tissue regeneration capacities will facilitate the use of such cells and their translation to regenerative medicine.

Repair of critical-size defects with autogenous periosteum-derived cells combined with bovine anorganic apatite/collagen: an experimental study in rat calvaria

The aim of this study was to evaluate the bone repair using autogenous periosteum-derived cells (PDC) and bovine anorganic apatite and collagen (HA-COL). PDC from Wistar rats (n=10) were seeded on HA-COL discs and subjected to osteoinduction during 6 days. Critical-size defects in rat calvarias were treated with blood clot (G1), autogenous bone (G2), HA-COL (G3) and HA-COL combined with PDC (G4) (n=40), and then analyzed 1 and 3 months after surgeries. Radiographic analysis exhibited no significant temporal change. G1 and G2 had discrete new marginal bone, but the radiopacity of graft materials in G2, G3 and G4 impaired the detection of osteogenesis. At 3 months, histopathological analysis showed the presence of ossification islets in G1, which was more evident in G2, homogeneous new bone around HA-COL in G3 and heterogeneous new bone around HA-COL in G4 in addition to moderate presence of foreign body cells in G3 and G4. Histomorphometric analysis showed no change in the volume density of xenograft (p>0.05) and bone volume density in G2 was twice greater than in G1 and G4 after 3 months (p<0.05), but similar to G3. The PDC did not increase bone formation in vivo, although the biomaterial alone showed biocompatibility and osteoconduction capacity.