Jerry I. Huang

Multilineage Cells from Human Adipose Tissue: Implications for Cell-Based Therapies

Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

Bone induction by BMP-2 transduced stem cells derived from human fat.

Purpose: We have isolated pluripotent mesenchymal progenitor cells in large numbers from liposuction aspirates (processed lipoaspirate cells or PLAs). This study examines the osteogenic potential of PLAs and bone marrow aspirate cells (BMAs), when exposed to either recombinant human bone morphogenetic protein (BMP)‐2 (rh‐BMP‐2) or adenovirus containing BMP‐2 cDNA (Ad‐BMP‐2).

RAT EXTRAMEDULLARY ADIPOSE TISSUE AS A SOURCE OF OSTEOCHONDROGENIC PROGENITOR CELLS

Human liposuction aspirates contain pluripotent adipose-derived mesodermal stem cells that have previously been shown to differentiate into various mesodermal cell types, including osteoblasts and chondrocytes. To develop an autologous research model of bone and cartilage tissue engineering, the authors sought to determine whether rat inguinal fat pads contain a similar population of osteochondrogenic precursor cells. It was hypothesized that the rat inguinal fat pad contains adipose-derived multipotential cells that resemble human adipose-derived mesodermal stem cells in their osteochondrogenic capacity. To test this, the authors assessed the ability of cells isolated from the rat inguinal fat pad to differentiate into osteoblasts and chondrocytes by a variety of lineage-specific histologic stains. Rat inguinal fat pads were isolated and processed from Sprague-Dawley rats into a fibroblast-like cell population. Cell cultures were placed in pro-osteogenic media containing dexamethasone, ascorbic acid, and beta-glycerol phosphate. Osteogenic differentiation was assessed at 2, 4, and 6 weeks. Alkaline phosphatase activity and von Kossa staining were performed to assess osteoblastic differentiation and the production of a calcified extracellular matrix. Cell cultures were also placed in prochondrogenic conditions and media supplemented with transforming growth factor-beta1, insulin, transferrin, and ascorbic acid. Chondrogenic differentiation was assessed at 2, 7, and 14 days by the presence of positive Alcian blue staining and type II collagen immunohistochemistry. Cells placed in osteogenic conditions changed in structure to a more cuboidal shape, formed bone nodules, stained positively for alkaline phosphatase activity, and secreted calcified extracellular matrix by 2 weeks. Cells placed in chondrogenic conditions formed cartilaginous nodules within 48 hours that stained positively for Alcian blue and type II collagen. The authors identified the rat inguinal fat pad as a source of osteochondrogenic precursors and developed a straightforward technique to isolate osteochondrogenic precursors from a small animal source. This relatively easily obtained source of osteochondrogenic cells from the rat may be useful for study of tissue engineering strategies and the basic science of stem cell biology.

Chondrogenic potential of multipotential cells from human adipose tissue

The use of stem cells for cell-based tissue-engineering strategies represents a promising alternative for the repair of cartilaginous defects. The multilineage potential of a population of putative mesodermal stem cells obtained from human lipoaspirates, termed processed lipoaspirate cells, was previously characterized. The chondrogenic potential of those cells was confirmed with a combination of histological and molecular approaches. Processed lipoaspirate cells under high-density micromass culture conditions, supplemented with transforming growth factor-&bgr;1, insulin, transferrin, and ascorbic acid, formed well-defined nodules within 48 hours of induction and expressed the cartilaginous markers collagen type II, chondroitin-4-sulfate, and keratan sulfate. Reverse transcription polymerase chain reaction analysis confirmed the expression of collagen type II and the cartilage-specific proteoglycan aggrecan. In summary, human adipose tissue may represent a novel plentiful source of multipotential stem cells capable of undergoing chondrogenesis in vitro.

Healing of a critical-sized defect in the rat femur with use of a vascularized periosteal flap, a biodegradable matrix, and bone morphogenetic protein

BACKGROUND The purpose of this study was to evaluate the osseous healing of a critical-sized femoral defect in a rat model with use of recombinant human bone morphogenetic protein-2 (rhBMP-2), a matrix fabricated of D,D-L,L-polylactic and hyaluronan acid (OPLA-HY), and a vascularized periosteal flap. METHODS The carrier matrix OPLA-HY with or without rhBMP-2 was implanted in a 1-cm-long femoral defect and secured with a plate and screws. In some groups, a vascularized periosteal flap was harvested from the medial surface of the tibia. In group 1, the femoral defects in the animals were filled with the OPLA-HY matrix alone; in group 2, the OPLA-HY matrix was covered by the vascularized periosteal flap; in group 3, 20 mug of rhBMP-2 was added to the OPLA-HY matrix; and in group 4, the femoral defect containing the OPLA-HY matrix and 20 mug of rhBMP-2 was wrapped circumferentially by the vascularized periosteal flap. The presence and density of new bone formation in the femoral defect were evaluated radiographically, histologically, and with histomorphometry at four and eight weeks postoperatively. RESULTS Groups 1 and 2, which were not treated with rhBMP-2, showed no radiographic or histologic evidence of mature bone formation at four or eight weeks. Both groups 3 and 4, which were treated with rhBMP-2, demonstrated excellent bone formation. However, with the periosteal flap, group 4 demonstrated more bone formation on histomorphometric analysis at eight weeks (43.1%) than did group 3 (28.3%) (p < 0.01). Additionally, heterotopic bone formed outside the boundaries of the defect in eight of the fifteen animals in group 3, which had no periosteal flap. CONCLUSIONS Bone-tissue engineering with use of the OPLA-HY matrix and rhBMP-2 produced good bone formation in the rat femoral defect model. However, the addition of a vascularized periosteal flap significantly increased bone formation within the boundaries of the defect and prevented heterotopic ossification.

Lunate arthroplasty with autologous mesenchymal stem cells in a rabbit model

BACKGROUND There is no ideal treatment for end-stage degenerative wrist disorders and subsequent carpal collapse. The purpose of this study was to investigate whether autologous cartilage constructs tissue-engineered from bone-marrow-derived mesenchymal stem cells can be effective for carpal bone reconstruction. METHODS Total lunate excision was performed in twenty-seven adult New Zealand White rabbits. Mesenchymal stem cells were isolated from marrow and then were culture-expanded. Group-1 rabbits underwent excision only. Group-2 animals underwent excision followed by implantation of a scaffold consisting of gelatin and hyaluronan. Group-3 animals underwent excision followed by implantation of a mesenchymal stem cell-seeded scaffold that had been preincubated in chondrogenic medium. The group-1 animals were killed at six weeks, whereas the group-2 and group-3 animals were killed at six or twelve weeks. Tissues were harvested for radiographic and histologic analysis. RESULTS Significant carpal collapse (a 5.4% +/- 2.8% reduction in the carpometacarpal index, p < 0.05) was observed in the group-1 animals by six weeks. In contrast, the carpal height was maintained in the group-2 and 3 animals. There was no radiographic evidence of ossification in the group-1 or 2 animals, whereas there was radiographic evidence of ossification in all six group-3 rabbits killed at the twelve-week time-point. Histologic sections from the group-3 animals showed filling of the lunate space with islands of cartilage with interspersed bone ossicles at six weeks. At twelve weeks, there was abundant bone formation as well as evidence of neovascularization. Osseous tissue was present in the central portions of the constructs while the periphery was lined with cartilage. In groups 1 and 2, the lunate space was filled with poorly organized fibrous tissue. CONCLUSIONS Cartilaginous implants preformed from autologous mesenchymal stem cells seeded onto biodegradable scaffold can prevent carpal collapse. The newly formed osteochondral tissue appears to function as an adequate biologic lunate spacer for at least twelve weeks in this animal model.

Functional Outcome After Open Reduction Internal Fixation of Intra-articular Fractures of the Distal Humerus in the Elderly

Objective: We conducted a study to evaluate the functional outcomes of elderly patients after open reduction internal fixation of intra-articular distal humerus fractures. Design: Retrospective clinical and radiographic evaluation. Setting: A Level I trauma and tertiary referral center. Patients/Participants: We identified 23 eligible patients aged older than 65 years from the centers orthopaedic trauma registry between 1997 and 2005. Fourteen patients were available for follow-up. We had a mean follow-up of 51 months with a range of 20 to 99 months. Intervention: All enrolled patients were acutely treated with open reduction internal fixation of their distal humerus. Main Outcome Measurements: All enrolled patients were contacted and evaluated radiographically and with physical examination. Functional outcome was assessed with the Mayo Elbow Performance, Disabilities of Arm and Shoulder and Hand, and Musculoskeletal Functional Assessment functional questionnaires. Results: All 14 fractures united. The mean Mayo Elbow Performance score was 83. The mean elbow flexion-extension arc was 20° to 120°. There was no significant loss of forearm pronation-supination (P > 0.05) or grip strength (32.6 versus 34.0 lbs, P > 0.05) compared with the contralateral arm. The mean Disabilities of Arm and Shoulder and Hand score was 37.6. Musculoskeletal Functional Assessment scores demonstrated disability with a mean total score of 33.4 (normative 9.3), hand score of 34.7 (normative 3.7), and self-care score of 31.8 (normative 1.7). One patient required reoperation for a disabling flexion contracture. Conclusions: Intra-articular distal humerus fractures are severely disabling injuries, particularly in the elderly population. Good results can be achieved with stable fixation and fracture union. Despite reasonable range of motion, patient-directed questionnaires revealed persistent pain and functional limitations.

Surgical management of posttraumatic elbow arthrofibrosis

BACKGROUND: Functional loss of motion is a frequent complication after elbow trauma. The purpose of this study was to determine the effectiveness of open elbow release in restoring functional elbow motion. METHODS: A retrospective chart review of 177 adult patients who underwent open elbow release at our institution by the senior surgeon (D.P.H.) from 2003 to 2010 was performed. Seventy-seven of the elbow contracture releases were performed for posttraumatic elbow stiffness, with loss of flexion-extension. Burns and isolated proximal radioulnar exostosis resections were excluded. The mean age of patients was 45 years (range, 20–76 years), with 68 patients demonstrating radiographic evidence of heterotopic ossification (HO). The mean preoperative flexion-extension arc was 51 degrees. All patients were treated with the same surgical protocol, which included circumferential elbow capsulectomy, HO excision, hardware removal, and ulnar nerve neurolysis with submuscular anterior transposition. RESULTS: At a mean follow-up of 12 months (range, 3–56 months), the mean elbow flexion-extension arc was 109 degrees representing a mean gain of 58 degrees. Sixty-nine percent (53 of 77 patients) achieved a minimum 100-degree functional elbow arc of motion. Six patients (8%) developed recurrent HO, with four undergoing secondary HO excision. One additional patient required manipulation under anesthesia in the early postoperative period. Complications included five infections, one postoperative fracture, one postoperative hematoma, and one radial head implant loosening. CONCLUSION: Open elbow contracture release and HO excision is an effective means of restoring functional elbow range of motion with a low complication rate. Furthermore, recurrent HO formation and elbow arthrofibrosis respond well to repeat surgical excision and contracture release. LEVEL OF EVIDENCE: IV, therapeutic study.

Anatomy and Biomechanics of the Distal Radioulnar Joint

The distal radioulnar joint (DRUJ) is a complex articulation allowing significant rotational and translational motion. Stability of the DRUJ depends on bony contact, intrinsic stabilizers of the triangular fibrocartilage complex, and extrinsic stabilizers of the distal forearm. Understanding the anatomy of this articulation is paramount in clinical decision making for the treatment of disorders involving the DRUJ.

Measurement scales in clinical research of the upper extremity, part 2: outcome measures in studies of the hand/wrist and shoulder/elbow.

Part 1 of this article outlined the basic characteristics of useful clinical measurement instruments and described scales used to measure general health, pain, and patient satisfaction. Part 2 describes the features of some of the scales most commonly used in clinical research in the hand, wrist, elbow, and shoulder.