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Growth factor release by vesicular phospholipid gels: in-vitro results and application for rotator cuff repair in a rat model.

Buchmann S, Sandmann GH, Walz L, Reichel T, Beitzel K, Wexel G, Tian W, Battmann A, Vogt S, Winter G, Imhoff AB - BMC Musculoskelet Disord (2015)

Bottom Line: Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups.Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness.The VPG itself was well tolerated and had no negative influence on the healing behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr., 81675, Munich, Germany. stefan.buchmann@LRZ.tu-muenchen.de.

ABSTRACT

Background: Biological augmentation of rotator cuff repair is of growing interest to improve biomechanical properties and prevent re-tearing. But intraoperative single shot growth factor application appears not sufficient to provide healing support in the physiologic growth factor expression peaks. The purpose of this study was to establish a sustained release of granulocyte-colony stimulating factor (G-CSF) from injectable vesicular phospholipid gels (VPGs) in vitro and to examine biocompatibility and influence on histology and biomechanical behavior of G-CSF loaded VPGs in a chronic supraspinatus tear rat model.

Methods: G-CSF loaded VPGs were produced by dual asymmetric centrifugation. In vitro the integrity, stability and release rate were analyzed. In vivo supraspinatus tendons of 60 rats were detached and after 3 weeks a transosseous refixation with G-CSF loaded VPGs augmentation (n = 15; control, placebo, 1 and 10 μg G-CSF/d) was performed. 6 weeks postoperatively the healing site was analyzed histologically (n = 9; H&E by modified MOVIN score/Collagen I/III) and biomechanically (n = 6).

Results: In vitro testing revealed stable proteins after centrifugation and a continuous G-CSF release of up to 4 weeks. Placebo VPGs showed histologically no negative side effects on the healing process. Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups. Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness.

Conclusions: By use of VPGs a continuous growth factor release could be obtained in vitro. The in vivo results demonstrate an improvement of immunohistology and biomechanical properties with a low dose G-CSF application via VPG. The VPG itself was well tolerated and had no negative influence on the healing behavior. Due to the favorable properties (highly adhesive, injectable, biocompatible) VPGs are a very interesting option for biologic augmentation. The study may serve as basis for further research in growth factor application models.

No MeSH data available.


Related in: MedlinePlus

Biomechanical testing setup. A) Ball-beared mounting clamp for fixation of the cryoclamp in a mechanical testing machine (Zwicki 1120, Fa. Zwick) B) Rat supraspinatus tendon press-fixed in a cryoclamp and humerus placed in a mounting grid with bony humeral fixation for load to failure testing.
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Fig2: Biomechanical testing setup. A) Ball-beared mounting clamp for fixation of the cryoclamp in a mechanical testing machine (Zwicki 1120, Fa. Zwick) B) Rat supraspinatus tendon press-fixed in a cryoclamp and humerus placed in a mounting grid with bony humeral fixation for load to failure testing.

Mentions: After scarification, the complete supraspinatus muscle was resected from the scapula in toto in 6 rats of each group and the humero-ulnary joint was disarticulated. Each specimen was frozen at −18°C separately and slowly thawed under room temperature for testing. During testing the thawed supraspinatus tendon was constantly moistened with sprayed isotone solution of sodium chlorid to anticipate drying out. Subsequently the proximal end (musculotendinous junction) was press-fixed in a cryoclamp while the humerus was placed in a mounting grid with bony humeral fixation (Figure 2A). Testing was performed with the shoulder at 90° of abduction. Cooling down the cryoclamp with 5 ml of liquid nitrogen (same amount on both sides of clamp) caused freezing of the clamp and the musculotendinous junction for rigid fixation, without affecting the free tendon (room temperature). The tendons were then mounted onto a mechanical testing machine (Zwicki 1120, Fa. Zwick) (Figure 2B). The construct was initially set to a pre-load of 0.1 N straightening and adjustment of each tendon. A dynamic preconditioning in 10 cycles with a speed of 0.2 mm/min between 0.1 and 0.5 N was performed. Five seconds after preconditioning the specimen was axially pulled at a constant speed of 10 mm/min until maximum load to failure [20]. Simultaneously contralateral tendons were tested in the same way for further investigation and percentage statistical analysis. Stiffness [N/mm] and ultimate failure load [N] were calculated with SPSS software (SPSS v12.0; SPSS, Chicago, Illinois).Figure 2


Growth factor release by vesicular phospholipid gels: in-vitro results and application for rotator cuff repair in a rat model.

Buchmann S, Sandmann GH, Walz L, Reichel T, Beitzel K, Wexel G, Tian W, Battmann A, Vogt S, Winter G, Imhoff AB - BMC Musculoskelet Disord (2015)

Biomechanical testing setup. A) Ball-beared mounting clamp for fixation of the cryoclamp in a mechanical testing machine (Zwicki 1120, Fa. Zwick) B) Rat supraspinatus tendon press-fixed in a cryoclamp and humerus placed in a mounting grid with bony humeral fixation for load to failure testing.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4417541&req=5

Fig2: Biomechanical testing setup. A) Ball-beared mounting clamp for fixation of the cryoclamp in a mechanical testing machine (Zwicki 1120, Fa. Zwick) B) Rat supraspinatus tendon press-fixed in a cryoclamp and humerus placed in a mounting grid with bony humeral fixation for load to failure testing.
Mentions: After scarification, the complete supraspinatus muscle was resected from the scapula in toto in 6 rats of each group and the humero-ulnary joint was disarticulated. Each specimen was frozen at −18°C separately and slowly thawed under room temperature for testing. During testing the thawed supraspinatus tendon was constantly moistened with sprayed isotone solution of sodium chlorid to anticipate drying out. Subsequently the proximal end (musculotendinous junction) was press-fixed in a cryoclamp while the humerus was placed in a mounting grid with bony humeral fixation (Figure 2A). Testing was performed with the shoulder at 90° of abduction. Cooling down the cryoclamp with 5 ml of liquid nitrogen (same amount on both sides of clamp) caused freezing of the clamp and the musculotendinous junction for rigid fixation, without affecting the free tendon (room temperature). The tendons were then mounted onto a mechanical testing machine (Zwicki 1120, Fa. Zwick) (Figure 2B). The construct was initially set to a pre-load of 0.1 N straightening and adjustment of each tendon. A dynamic preconditioning in 10 cycles with a speed of 0.2 mm/min between 0.1 and 0.5 N was performed. Five seconds after preconditioning the specimen was axially pulled at a constant speed of 10 mm/min until maximum load to failure [20]. Simultaneously contralateral tendons were tested in the same way for further investigation and percentage statistical analysis. Stiffness [N/mm] and ultimate failure load [N] were calculated with SPSS software (SPSS v12.0; SPSS, Chicago, Illinois).Figure 2

Bottom Line: Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups.Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness.The VPG itself was well tolerated and had no negative influence on the healing behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technical University of Munich, Ismaningerstr., 81675, Munich, Germany. stefan.buchmann@LRZ.tu-muenchen.de.

ABSTRACT

Background: Biological augmentation of rotator cuff repair is of growing interest to improve biomechanical properties and prevent re-tearing. But intraoperative single shot growth factor application appears not sufficient to provide healing support in the physiologic growth factor expression peaks. The purpose of this study was to establish a sustained release of granulocyte-colony stimulating factor (G-CSF) from injectable vesicular phospholipid gels (VPGs) in vitro and to examine biocompatibility and influence on histology and biomechanical behavior of G-CSF loaded VPGs in a chronic supraspinatus tear rat model.

Methods: G-CSF loaded VPGs were produced by dual asymmetric centrifugation. In vitro the integrity, stability and release rate were analyzed. In vivo supraspinatus tendons of 60 rats were detached and after 3 weeks a transosseous refixation with G-CSF loaded VPGs augmentation (n = 15; control, placebo, 1 and 10 μg G-CSF/d) was performed. 6 weeks postoperatively the healing site was analyzed histologically (n = 9; H&E by modified MOVIN score/Collagen I/III) and biomechanically (n = 6).

Results: In vitro testing revealed stable proteins after centrifugation and a continuous G-CSF release of up to 4 weeks. Placebo VPGs showed histologically no negative side effects on the healing process. Histologically in vivo testing demonstrated significant advantages for G-CSF 1 μg/d but not for G-CSF 10 μg/d in Collagen III content (p = 0.035) and a higher Collagen I/III ratio compared to the other groups. Biomechanically G-CSF 1 μg/d revealed a significant higher load to failure ratio (p = 0.020) compared to control but no significant differences in stiffness.

Conclusions: By use of VPGs a continuous growth factor release could be obtained in vitro. The in vivo results demonstrate an improvement of immunohistology and biomechanical properties with a low dose G-CSF application via VPG. The VPG itself was well tolerated and had no negative influence on the healing behavior. Due to the favorable properties (highly adhesive, injectable, biocompatible) VPGs are a very interesting option for biologic augmentation. The study may serve as basis for further research in growth factor application models.

No MeSH data available.


Related in: MedlinePlus