Corrigendum to "Pulsed Electromagnetic Fields Improve Tenogenic Commitment of Umbilical Cord-Derived Mesenchymal Stem Cells: A Potential Strategy for Tendon Repair-An In Vitro Study".

[This corrects the article DOI: 10.1155/2018/9048237.].

Pulsed Electromagnetic Fields Improve Tenogenic Commitment of Umbilical Cord-Derived Mesenchymal Stem Cells: A Potential Strategy for Tendon Repair-An In Vitro Study.

Tendon repair is a challenging procedure in orthopaedics. The use of mesenchymal stem cells (MSCs) and pulsed electromagnetic fields (PEMF) in tendon regeneration is still investigational. In this perspective, MSCs isolated from the human umbilical cord (UC) may represent a possible candidate for tendon tissue engineering. The aim of the study is to evaluate the effect of low-frequency PEMF on tenogenic differentiation of MSCs isolated from the human umbilical cord (UC-MSCs) in vitro. 15 fresh UC samples from women with healthy pregnancies were retrieved at the end of caesarean deliveries. UC samples were manually minced into small fragments (less than 4 mm length) and cultured in MSC expansion medium. Part of the UC-MSCs was subsequently cultured with PEMF and tenogenic growth factors. UC-MSCs were subjected to pulsed electromagnetic fields for 2 h/day, 4 h/day, or 8 h/day. UC-MSCs cultured with FGF-2 and stimulated with PEMF showed a greater production of collagen type I and scleraxis. The prolonged exposure to PEMF was also related to the greatest expression of tenogenic markers. Thus, the exposure to PEMF provides a positive preconditioning biophysical stimulus, which may enhance UC-MSC tenogenic potential.

The Degree of Chondral Fragmentation Affects Extracellular Matrix Production in Cartilage Autograft Implantation: An In Vitro Study.

PURPOSE: To evaluate if the degree of chondral fragmentation affected extracellular matrix (ECM) production in cartilage fragment autograft implantation in vitro. METHODS: Cartilage was taken from 5 donors undergoing total hip replacement (mean age, 65.6 years; standard deviation [SD], 3). The cartilage was minced to obtain 4 groups with different fragment sizes: (1) "fish scale" (diameter, 8 mm; thickness, 0.3 mm), (2) cubes with 2-mm sides, (3) cubes with 1-mm sides, and (4) cartilage paste (< 0.3 mm). The cultures were maintained in chondrogenic medium for 6 weeks. Biochemically, a proteoglycan (PG):DNA ratio was calculated as the best approximation of ECM production per cell. The ratio between PG released in the culture medium and the PG in the neocartilage (PGrel:PG) was used as a matrix stability index. Histologically, the slides were stained with safranin O fast green and collagen type II immunostaining. The titration of safranin O-positive cells and the Bern score were calculated. RESULTS: Regarding the PG:DNA ratio, group 4 performed significantly better than groups 1 (P = .001) and 3 (P = .02), whereas group 2 performed better than group 1 (P = .03). No significant difference was found regarding the PGrel:PG ratio and safranin O-positive cells. Regarding the Bern score, group 4 performed significantly better than groups 1 (P = .02), 2 (P = .04), and 3 (P = .03). CONCLUSIONS: We conclude that human cartilage fragmentation significantly affects ECM production in vitro. Increased fragmentation enhances ECM production. CLINICAL RELEVANCE: Assuming a similar behavior in vivo, we recommend mincing the cartilage into small pieces when performing the cartilage fragment autograft implantation technique in order to increase ECM production. Further in vitro studies investigating cartilage of younger nonarthritic donors, as well as in vivo studies, are needed.

Bone marrow derived stem cells in joint and bone diseases: a concise review.

Stem cells have huge applications in the field of tissue engineering and regenerative medicine. Their use is currently not restricted to the life-threatening diseases but also extended to disorders involving the structural tissues, which may not jeopardize the patients' life, but certainly influence their quality of life. In fact, a particularly popular line of research is represented by the regeneration of bone and cartilage tissues to treat various orthopaedic disorders. Most of these pioneering research lines that aim to create new treatments for diseases that currently have limited therapies are still in the bench of the researchers. However, in recent years, several clinical trials have been started with satisfactory and encouraging results. This article aims to review the concept of stem cells and their characterization in terms of site of residence, differentiation potential and therapeutic prospective. In fact, while only the bone marrow was initially considered as a "reservoir" of this cell population, later, adipose tissue and muscle tissue have provided a considerable amount of cells available for multiple differentiation. In reality, recently, the so-called "stem cell niche" was identified as the perivascular space, recognizing these cells as almost ubiquitous. In the field of bone and joint diseases, their potential to differentiate into multiple cell lines makes their application ideally immediate through three main modalities: (1) cells selected by withdrawal from bone marrow, subsequent culture in the laboratory, and ultimately transplant at the site of injury; (2) bone marrow aspirate, concentrated and directly implanted into the injury site; (3) systemic mobilization of stem cells and other bone marrow precursors by the use of growth factors. The use of this cell population in joint and bone disease will be addressed and discussed, analysing both the clinical outcomes but also the basic research background, which has justified their use for the treatment of bone, cartilage and meniscus tissues.

A future in our past: the umbilical cord for orthopaedic tissue engineering.

The umbilical cord (UC) has recently been added to the list of potential cell sources for tissue engineering and regenerative medicine purposes. Although the UC is usually discarded after delivery, UC storage in special tissue banks is becoming an increasingly common procedure. Indeed, the capacity of UC cells to be directed toward different phenotypes makes this tissue an ideal cell source for regenerative medicine in orthopedics and in other fields. In this paper, these issues are presented and discussed, together with the potential of this cell source for allogeneic use. This article also looks at the anatomy of the UC from both the macroscopic and the cellular perspective and considers its extraordinary potential for research and clinical applications.

Autologous cartilage fragments in a composite scaffold for one stage osteochondral repair in a goat model.

We propose a culture-free approach to osteochondral repair with minced autologous cartilage fragments loaded onto a scaffold composed of a hyaluronic acid (HA)-derived membrane, platelet-rich fibrin matrix (PRFM) and fibrin glue. The aim of the study was to demonstrate in vitro the outgrowth of chondrocytes from cartilage fragments onto this scaffold and, in vivo, the formation of functional repair tissue in goat osteochondral defects. Two sections were considered: 1) in vitro: minced articular cartilage from goat stifle joints was loaded onto scaffolds, cultured for 1 or 2 months, and then evaluated histologically and immunohistochemically; 2) in vivo: 2 unilateral critically-sized trochlear osteochondral defects were created in 15 adult goats; defects were treated with cartilage fragments embedded in the scaffold (Group 1), with the scaffold alone (Group 2), or untreated (Group 3). Repair processes were evaluated morphologically, histologically, immunohistochemically and biomechanically at 1, 3, 6 and 12 months. We found that in vitro, chondrocytes from cartilage fragments migrated to the scaffold and, at 2 months, matrix positive for collagen type II was observed in the constructs. In vivo, morphological and histological assessment demonstrated that cartilage fragment-loaded scaffolds led to the formation of functional hyaline-like repair tissue. Repair in Group 1 was superior to that of control groups, both histologically and mechanically. Autologous cartilage fragments loaded onto an HA/PRFM/fibrin glue scaffold provided a viable cell source and allowed for an improvement of the repair process of osteochondral defects in a goat model, representing an effective alternative for one-stage repair of osteochondral lesions.