The Enhancing Effect of Mechanical Stimulation on the Chondrogenic Function of Infrapatellar Fat Pad Stem Cells

Summary

This study focuses on developing a multimodal technology combining cyclic tensile mechanical stimulation (10% strain, 1 Hz) with infrapatellar fat pad-derived stem cells (IPFP-SCs) therapy, investigating their synergistic effects on promoting chondrogenic differentiation of IPFP-SCs, and establishing a more efficient regenerative strategy for cartilage tissue engineering.

Abstract

The infrapatellar fat pad (IPFP), a specialized fibrofatty structure within the anterior compartment of the knee joint, is characterized by a unique microarchitecture featuring interspersed collagen bundles and adipose lobules, which collectively establish its viscoelastic biomechanical properties. Emerging evidence highlights the distinctive transcriptional profile of IPFP-SCs, specifically their association with cartilage degradation mediators during osteoarthritis progression. Recent research demonstrates that dynamic compression and hydrostatic pressure effectively enhance chondrogenic differentiation of both bone marrow-derived and IPFP-derived mesenchymal stem cells while inhibiting calcification deposition. This study utilized a cell stretching system to simulate the cyclic mechanical stress environment of the knee joint, demonstrating that dynamic tensile stimulation (10% strain, 1 Hz) significantly enhances the chondrogenic differentiation capacity of IPFP-SCs. This enhancement was manifested by upregulated expression of chondrogenic markers, including SOX9 and COMP, confirming that the joint-specific mechanical microenvironment plays a critical regulatory role in the terminal differentiation of mesenchymal stem cells. These results provide crucial experimental evidence for cartilage tissue regeneration strategies, emphasizing the importance of biomechanical modulation in regenerative therapies for cartilage repair.

Introduction

The regeneration and repair of cartilage tissue represent a central challenge in osteoarthritis treatment, as conventional cell therapies often fail to reconstruct functional cartilage matrices due to inadequate microenvironmental regulation. In recent years, multimodal strategies integrating physical mechanical stimulation with cell therapy have emerged as a research hotspot¹, aiming to enhance the chondrogenic differentiation potential of stem cells by simulating in vivo biomechanical microenvironments. This study focuses on developing a multimodal technology combining cyclic tensile mechanical stimulation (10% strain, 1 Hz) with IPF....

Protocol

The study was performed in compliance with the Institutional guidelines and was approved by the Ethics Committee of Inner Mongolia Autonomous Region People's Hospital(SC-07/01KT2024008). The reagents and the equipment used are listed in the Table of Materials.

1. Thawing and expansion of IPFP-SCs

1. Thaw IPFP-SCs.
   1. Rapidly thaw cryopreserved IPFP-SCs (P2-P5) in a 37 °C water bath.
   2. Transfer the cells into a 15 mL centrifuge tube containing pre-warmed complete growth medium (α-DMEM + 10% FBS + 1% penicillin/streptomycin).
   3. Centrifuge at 300 × g

Results

The representative findings of this study demonstrate that cyclic tensile mechanical stimulation enhances the chondrogenic differentiation of IPFP-SCs under chondrogenic induction. Specifically, IPFP-SCs subjected to 7-day tensile loading exhibited significant upregulation of chondrogenic markers at both transcriptional levels, as evidenced by increased SOX9 expression and COMP production compared to static control groups. These coordinated molecular and structural responses confirm that biomechanical s.......

Discussion

The protocol outlined integrates cyclic tensile mechanical stimulation (10% strain, 1 Hz) with IPFP-SCs to enhance chondrogenic differentiation, addressing critical challenges in cartilage regeneration. Key steps include precise cell expansion, staged chondrogenic pre-culture (3 days), delayed mechanical stimulation (initiated at Day 3 for 7 days), and post-stimulation analysis via immunofluorescence (SOX9, COMP) and qPCR. The mechanical stimulation of protocol, informed by prior mechanobiological studi.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
4% Paraformaldehyde	biosharp	BL539A
Anti-Fluorescence Quenching Blocking Solution (containing DAPI)	Beyotime	P0131
Blocking Solution	Beyotime	P0260
Cell Culture Chamber	AIRTECH	AZ2020062530
Cell Tank	CELL &FORCE
Col II Primary Antibody	Abcam	AB34712
E.Z.N.A. HP Total RNA Kit	OMEGA	R6812-00S
F-actin Primary Antibody	Proteintech	PF00001
Fetal Bovine Serum	CellMax	SA101.02
Goat to Rb IgG	Abcam	AB50077
Hieff qPCR SYBR Green Master Mix(Low Rox Plus)	YEASEN	11202ES50
Human Mesenchymal Stem Cell Chondrogenic Induction Kit	Fuyuanbio	FY200008
Leica DMi8 inverted biomicroscope	LEICA	DMi8
LightCycler 96 Instrument	Roche	16056
MEM-α	Gibco	C12571500BT
PBS	Servicebio	G4202
Penicillin-Streptomycin-Amphotericin B	NCM Biotech	C100C8
Piezo1 Primary Antibody	Proteintech	15939-1-AP
PrimeScript RT reagent Kit (Perfect Real Time)	Takara	RR037A
SOX9 Primary Antibody	Abcam	AB185230
TritonX-100	SCIGE	SG6193
Veriti Dx 96-well Thermal Cycler	Thermo Fisher	EN61326