Broad-Spectrum Protease Application in Tissue Digestion and Primary Cell Isolation

The key to primary cell isolation does not lie in simply increasing the speed at which a tissue is “digested open,” but rather in establishing a controllable balance among extracellular matrix dissociation, loosening of cell-cell junctions, and dispersion of tissue fragments, while preserving cell viability, membrane integrity, surface markers, and downstream culture suitability as much as possible. In this process, broad-spectrum proteases usually do not undertake complete tissue degradation on their own. Instead, they function as junction-loosening enzymes, basement membrane-assisting dissociation enzymes, or enhanced dissociation enzymes for complex samples, acting together with collagenase, hyaluronidase, DNase I, and termination/inhibition systems to improve the quality of single-cell release.

 

Keywords: tissue digestion; primary cell isolation; broad-spectrum protease; collagenase; neutral protease; pronase; papain; DNase I

 

1 Functional role of broad-spectrum proteases in tissue dissociation

1.1 Structural basis of tissue dissociation

(1) Extracellular matrix level

In most tissues, cells are not simply stacked together, but are embedded within a spatial structure composed of collagen fibers, basement membrane components, proteoglycans, and adhesion complexes. Tissue digestion therefore first confronts the problem of loosening the matrix scaffold.

(2) Cell-junction level

In some tissues, even after partial collagen degradation, cells may still remain aggregated through adherens junctions, tight junctions, desmosome-like structures, and membrane adhesion molecules. Accordingly, matrix degradation does not by itself mean that single-cell release has been completed.

(3) Sample viscosity level

During tissue mincing and enzymatic digestion, released DNA, protein fragments, and cellular contents can markedly increase suspension viscosity and promote cell aggregation, thereby further affecting filtration, sorting, and counting.

 

1.2 Functional levels of broad-spectrum proteases

(1) Loosening of junctional structures

The major value of broad-spectrum proteases lies in cleaving multiple protein-based junction sites, thereby weakening cell-cell and cell-basement membrane attachment.

(2) Dispersion of tissue fragments

After the primary digestion enzyme has already achieved partial matrix degradation, broad-spectrum proteases can further reduce tissue fragment integrity and decrease undigested residual material.

(3) Enhancement of the primary enzyme system

For most solid tissues, broad-spectrum proteases are more suitable as synergistic enzymes than as sole primary enzymes. Their methodological significance mainly lies in shortening collagenase exposure time, reducing mechanical pipetting intensity, and improving uniformity of the single-cell suspension.

 

1.3 Functional division relative to structural degradation enzymes

(1) Collagenase

Collagenase primarily undertakes degradation of collagen fibers and the stromal scaffold and is the foundational primary enzyme in most tissue digestion systems.

(2) Hyaluronidase

Hyaluronidase is mainly used to reduce hyaluronic acid-related viscoelasticity and improve tissue permeability, and is especially important in tissues rich in mucopolysaccharides.

(3) Broad-spectrum proteases

These mainly complement the loosening of junctional structures and dissociation of residual protein complexes, and are most suitable for use when “collagen has already been loosened but cells remain difficult to release.”

 

2 Common types of broad-spectrum proteases and their application features

2.1 Neutral proteases and Dispase-type systems

(1) Enzymatic characteristics

Neutral proteases and Dispase-type enzymes tend to more gently cleave basement membrane regions and junction-related proteins, and usually cause less overall damage to membrane surface structures than high-intensity trypsin systems.

(2) Suitable tissues

They are more suitable for epithelial tissues, glandular tissues, mammary tissues, lung tissues, and primary isolation systems requiring better preservation of surface antigens.

(3) Application boundary

Their direct degradation capacity against dense collagen-rich matrices is limited, so in highly matrix-rich samples they usually need to be combined with collagenase.

 

2.2 Pronase-type systems and Streptomyces-derived proteases

(1) Enzymatic characteristics

These systems are usually composed of multicomponent proteases, have broad substrate ranges, and possess relatively strong overall tissue-loosening capacity.

(2) Suitable tissues

They are more suitable for difficult-to-digest samples, such as complex parenchymal tissues, certain tumor tissues, matrix-rich tissues, and some neural tissue pretreatment systems.

(3) Application boundary

Because of their broad activity spectrum, they more strongly affect surface proteins, membrane integrity, and subsequent cell status, and are therefore more appropriate as enhanced auxiliary enzymes.

 

2.3 Papain

(1) Enzymatic characteristics

Papain is a relatively mild proteolytic system with high suitability for fragile primary cell isolation.

(2) Suitable tissues

It is often used in neural tissues, retinal tissues, and cell-release systems that are more sensitive to mechanical and enzymatic injury.

(3) Application boundary

Its independent dissociation ability is limited in highly collagenous, fibrotic, or very dense samples, so other enzymes are usually still required to complete primary matrix degradation.

 

2.4 Trypsin

(1) Enzymatic characteristics

Trypsin has a relatively defined cleavage preference for lysine- and arginine-related sites and produces rapid dissociation. It is widely used in cell culture and in redistribution of certain tissues.

(2) Suitable tissues

It is suitable for relatively loose tissues, systems with low requirements for surface antigen preservation, or scenarios focused on short-term redistribution.

(3) Application boundary

Its effects on membrane surface proteins and adhesion molecules are relatively pronounced, so prolonged high-intensity use is not advisable in flow sorting, primary culture, and surface-marker analysis systems.

 

2.5 Elastase

(1) Enzymatic characteristics

Elastase mainly targets elastin-related structures and is a more tissue-directed auxiliary digestion enzyme.

(2) Suitable tissues

It is suitable for certain lung tissues, vascular-related tissues, or samples rich in elastic fibers.

(3) Application boundary

It is not suitable as a routine primary enzyme and is better used as a supplementary component for lysis of specific tissue structures.

Table 1. Comparison of common broad-spectrum proteases in primary cell isolation

 

Enzyme Type	Main Functional Feature	More Suitable Tissues/Scenarios	Main Advantage	Main Limitation
Neutral protease / Dispase	Gentle weakening of basement membrane and junctional structures	Epithelial tissues, glandular tissues, systems requiring surface marker preservation	Viability and phenotype are relatively easier to control	Limited ability to process dense tissues alone
Pronase / Streptomyces protease	Multicomponent broad loosening	Difficult tissues, complex parenchymal tissues, some neural tissues	More complete dissociation and reduced residual tissue fragments	Higher risk of overdigestion
Papain	Mild proteolysis	Neural tissues, developmental tissues, fragile primary cells	Higher potential for preserving viability	Limited capacity for highly matrix-rich samples
Trypsin	Rapid loosening of junctions	Loose tissues, cultured cells, some embryonic tissues	Mature methodology and direct action	More likely to affect surface proteins and membrane integrity
Elastase	Auxiliary degradation of elastic structures	Lung tissues, samples rich in elastic fibers	Targeted for specific tissue structures	Limited general applicability

 

3 Synergistic enzyme systems and combination logic

3.1 Combination logic of collagenase and broad-spectrum proteases

(1) Matrix scaffold degradation

Collagenase is responsible for digesting the main interstitial scaffold and is the basis of most tissue digestion systems.

(2) Supplementary loosening of junctional structures

Broad-spectrum proteases are used to weaken residual protein-based junctions and basement membrane adhesion structures, thereby increasing single-cell release efficiency.

(3) Optimization of the digestion window

Compared with simply extending collagenase incubation time, adding an appropriate dose of broad-spectrum protease usually helps improve dissociation completeness while maintaining viability.

 

3.2 Role of DNase I in single-cell quality control

(1) Degradation of free DNA

DNA released during tissue disruption can markedly increase sample viscosity and induce cell aggregation. DNase I reduces suspension viscosity and improves filtration and resuspension quality.

(2) Improvement of single-cell proportion

For flow cytometry, single-cell sequencing, and primary culture systems, DNase I often improves the final single-cell state more effectively than simply increasing protease concentration.

 

3.3 Supplementary value of hyaluronidase and specific auxiliary enzymes

(1) Hyaluronic acid-rich samples

In tissues rich in mucopolysaccharides, hyaluronidase can improve tissue permeability and increase entry efficiency of the primary enzyme.

(2) Elastic-structure-rich samples

In tissues rich in elastic fibers, elastase can be used as a structure-directed auxiliary enzyme to improve dissociation efficiency.

 

3.4 Digestion termination and post-processing control

(1) Trypsin inhibition

If trypsin or redistribution proteases are used in the system, the termination step must be explicit, otherwise overdigestion will continue damaging cell surface proteins and membrane integrity.

(2) Gentle protection

For neural tissues, epithelial cells, and fragile primary cells, the termination system is not only used to “stop the enzyme,” but also to provide post-processing protection.

 

4 Application strategies in different tissue types

4.1 Epithelial and glandular tissues

(1) Tissue characteristics

Cells are tightly connected and the basement membrane structure is relatively intact.

(2) Recommended strategy

A combination of collagenase with neutral protease or Dispase-type systems is more suitable, in order to reduce mechanical pipetting intensity while preserving surface antigens.

(3) Key evaluation points

The single-cell proportion, epithelial marker preservation, and subsequent adherence capacity should be monitored simultaneously.

 

4.2 Neural tissues

(1) Tissue characteristics

Cells are fragile, rich in processes, and highly sensitive to both enzymatic and mechanical injury.

(2) Recommended strategy

Papain or other mild protease systems should be prioritized, together with DNase I. High-intensity, prolonged broad-spectrum protease treatment is not advisable.

(3) Key evaluation points

Viability, morphologic preservation, and downstream functional state are usually more important than total yield.

 

4.3 Tumor tissues and fibrotic samples

(1) Tissue characteristics

The matrix is complex, sample heterogeneity is high, and necrosis, blood background, and uneven residual tissue fragments are common.

(2) Recommended strategy

Collagenase should serve as the primary enzyme, supplemented with high-activity neutral protease or Pronase-type systems to improve loosening of tissue fragments and uniformity of cell release.

(3) Key evaluation points

Cell viability, debris proportion, surface marker preservation, and stability of immune-cell subsets all need to be monitored simultaneously.

 

4.4 Parenchymal organs

(1) Tissue characteristics

Parenchymal organs such as liver, lung, and kidney often contain parenchymal cells, stromal cells, endothelial cells, and immune cells simultaneously.

(2) Recommended strategy

A collagenase-dominant strategy combined with broad-spectrum protease assistance and DNase I synergy is more appropriate.

(3) Key evaluation points

If downstream sorting or culture is planned, phenotype compatibility of the different target cell types should be prioritized over total cell number alone.

Table 2. Typical roles of broad-spectrum proteases in different tissue types

 

Tissue Type	Common Difficulty	Main Role of Broad-Spectrum Protease	Main Issue Requiring Attention
Epithelial / glandular tissues	Tight junctions, intact basement membrane	Junction loosening and basement membrane-assisted dissociation	Preservation of surface markers
Neural tissues	Fragile cells, easy to injure	Mild auxiliary dissociation	Viability and morphologic preservation
Tumor / fibrotic tissues	Complex matrix, many residual tissue fragments	Improve completeness of dissociation	Viability and debris control
Parenchymal organs	Multiple cell types	Synergistic component for collagenase systems	Compatibility across multiple cell populations

 

5 Research products related to tissue digestion and primary cell isolation

Table 3. Product table for primary enzymes and broad-spectrum proteases in tissue digestion and primary cell isolation

 

Catalog No.	Name	Grade and Purity	Suitable Research Step / Use
C278962	Collagenase AF-1	EnzymoPure™, ≥3.00 U/mg	Suitable for primary digestion steps based mainly on collagen degradation and can serve as a foundational primary enzyme choice for solid tissue dissociation
C278986	Collagenase NB 1 From Clostridium Histolyticum	EnzymoPure™, Premium pure, ≥3.00 U/mg	Suitable for routine tissue dissociation systems with higher requirements for batch stability and purity
A1492720	Collagenase II from Clostridium histolyticum	ActiBioPure™, Bioactive, High Performance, EnzymoPure™, Native, ≥125 U/mg powder	Suitable for primary digestion of collagen-rich tissues
C1509223	Collagenase IV	Bioactive, ActiBioPure™, Native, High Performance, EnzymoPure™, ≥125 U/mg enzyme powder	Suitable for basement membrane-related tissues, epithelial tissues, and systems requiring better preservation of surface markers
C754912	Collagenase from Clostridium histolyticum	sterile-filtered, high purity, purified by chromatography, Type VII-S, ≥4 FALGPA units/mg solid, ≥700 CDU/mg solid	Suitable for tissue dissociation systems requiring high purity, viability, and single-cell quality
C278996	Collagenase NB 7D from Clostridium Histolyticum	EnzymoPure™, sterile, ≥0.2 U/mg powder	Suitable for tissue isolation systems requiring sterility and downstream primary culture compatibility
C128711	Collagenase from Clostridium histolyticum(Animal Origin Free,B)	EnzymoPure™, ActiBioPure™, Bioactive, High Performance, Animal Free, Native, ≥300 units/mg dry weight	Suitable for tissue digestion and primary cell isolation systems requiring animal-origin-free conditions
C754917	Collagenase from Clostridium histolyticum	sterile-filtered, suitable for release of physiologically active rat hepatocytes, Type IV-S, 0.5-5.0 FALGPA units/mg solid, ≥125 CDU/mg solid	Suitable for release of primary cells such as hepatocytes requiring preservation of physiologic activity
D195752	Dispase	EnzymoPure™, BioReagent, 50 U/mg	Suitable for gentle loosening of basement membranes and cell junctions; a commonly used auxiliary broad-spectrum protease for epithelial/glandular tissues
N278967	Neutral Protease AF From Clostridium Histolyticum	EnzymoPure™, ≥0.50 U/mg	Suitable for use together with collagenase to improve completeness of tissue dissociation
N279017	Neutral Protease NB From Clostridium Histolyticum	EnzymoPure™, High Active Grade, ≥4.00 U/mg	Suitable for tissue samples that are difficult to dissociate and require enhanced loosening of junctional structures
N128693	Neutral Protease from Bacillus polymyxa(Purified)	EnzymoPure™, ≥4 units/mg dry weight	Suitable for mild broad-spectrum proteolysis and auxiliary tissue loosening
P736615	Pronase, from Streptomyces griseus	EnzymoPure™, ~6000 units/g protein	Suitable for Pronase-type enhanced dissociation systems to further disperse complex tissue fragments
P755359	Protease from Streptomyces griseus	EnzymoPure™, ≥7000 units/g solid, powder	Suitable for broad-spectrum auxiliary digestion of difficult-to-digest tissues and complex parenchymal samples
P755282	Protease from Streptomyces sp.	Type XXI, ≥15 units/mg solid	Suitable for loosening broad protein-based junction structures and further dispersing tissue fragments
P123425	Papain	EnzymoPure™, lyophilized powder, ≥10 units/mg	Suitable for relatively mild tissue digestion, especially in fragile cell systems
P164463	Papain	Bioactive, ActiBioPure™, Native, High Performance, EnzymoPure™, ≥2000 U/mg enzyme powder	Suitable for neural tissues or primary cell release systems requiring high viability
P754923	Papain from Carica papaya	solution, light brown, ≥10 U/mg protein	Suitable for freshly prepared mild protease digestion systems
T274333	Trypsin	EnzymoPure™, 1:250，Tissue Culture Grade	Suitable for tissue culture and some tissue redistribution steps
R774505	Recombinant trypsin (cell culture grade)	Animal Free, Carrier Free, Bioactive, PharmPure™, ActiBioPure™, High Performance, for cell culture, EnzymoPure™, PBS Only, ≥95%(SDS-PAGE), ≥3800 USP unit/mg pro.	Suitable for gentle cell and tissue dissociation under animal-origin-free conditions
R1201958	Recombinant Trypsin Solution (W/O Phenol Red & EDTA)	BioReagent, for cell culture, sterile, 0.025 mg/mL	Suitable for cell/tissue dissociation systems requiring milder conditions or avoiding EDTA
R1202079	Recombinant Trypsin-EDTA Solution (W/O Phenol Red)	BioReagent, for cell culture, sterile, 0.05 mg/mL	Suitable for post-digestion redistribution of tissues and cell-culture-related dissociation steps
E128656	Elastase from porcine pancreas(Purified)	EnzymoPure™, ≥8 units/mg protein	Suitable for auxiliary dissociation of elastic fiber-related tissues, such as certain lung tissues or elastic matrix-rich samples
E107150	Elastase, pancreatic from porcine pancreas	EnzymoPure™, 30 units/mg	Suitable for addition into specific tissue digestion systems as an auxiliary enzyme for elastic structure lysis

 

Table 4. Product table for synergistic dissociation, aggregation control, and digestion termination in tissue digestion

 

Catalog No.	Name	Grade and Purity	Suitable Research Step / Use
D755014	Deoxyribonuclease I from bovine pancreas	Type IV, lyophilized powder, ≥2,000 Kunitz units/mg protein	Suitable for degrading free DNA during tissue digestion, reducing sample viscosity and cell aggregation
D755012	Deoxyribonuclease I from bovine pancreas	Type II, lyophilized powder, Protein≥80%, ≥2,000 units/mg protein	Suitable for aggregation control and optimization of single-cell suspensions in routine primary isolation
D755013	Deoxyribonuclease I from bovine pancreas	Type II-S, lyophilized powder, Protein≥80%, ≥2,000 units/mg protein	Suitable for tissue dissociation systems requiring relatively stable DNase activity
D406460	DNase I	Recombinant, PharmPure™, endotoxin tested, EnzymoPure™, ≥95%, 1.8KU/ml-2.2KU/ml	Suitable for primary isolation experiments with higher requirements for endotoxin background and system cleanliness
R1373644	Recombinant DNase I, RNase-free	EnzymoPure™, ≥95%(SDS-PAGE), 1 U/μl	Suitable for flow cytometry, single-cell sequencing, and other systems requiring RNA integrity and low background
H754463	Hyaluronidase	Bioactive, ActiBioPure™, Native, High Performance, EnzymoPure™, endotoxin tested, ≥1000 IU/mg，derived from bovine testicles	Suitable for loosening mucopolysaccharide-rich matrices in hyaluronic acid-rich tissues
H128644	Hyaluronidase from bovine testes	Bioactive, ActiBioPure™, High Performance, EnzymoPure™, Native, ≥300 USP/NF units/mg dry weight	Suitable for use with collagenase and broad-spectrum proteases to improve tissue permeability and single-cell release
H128645	Hyaluronidase from bovine testes(Purified)	EnzymoPure™, ≥3,000 USP/NF units/mg dry weight	Suitable for synergistic dissociation systems requiring higher activity and purity
H1492276	Hyaluronidase from sheep testes	Bioactive, ActiBioPure™, Native, endotoxin tested, High Performance, EnzymoPure™, ≥3000 IU/mg dry weight	Suitable for complex tissue dissociation systems requiring high-activity hyaluronidase
H1492277	Recombinant Hyaluronidase	ActiBioPure™, Bioactive, Animal Free, High Performance, EnzymoPure™, Recombinant, ≥95%(SDS-PAGE), >60000U/mL, >60000U/mg protein	Suitable for animal-origin-free and high-activity synergistic dissociation systems
C754904	Collagenase + protease inhibitor	2-5 FALGPA units/mg solid, ≥800 CDU/mg solid	Suitable for balanced digestion systems requiring both efficient tissue release and control of excessive proteolysis
S752084	Trypsin Inhibitor from Soybean	ActiBioPure™, Native, for cell culture, ≥0.7mg Trypsin/mg Inhibitor	Suitable for gentle termination of trypsin activity after cell culture and primary isolation
T1518361	Trypsin Inhibitor Solution (1 mg/mL)	1 mg/mL	Suitable for ready-to-use trypsin termination steps
T1518363	Trypsin Inhibitor Solution (5 mg/mL)	BioReagent, 5 mg/mL	Suitable for rapid termination in systems with relatively high trypsin load
T755849	Trypsin Inhibitor, Defined (1X) Solution	Animal Free, BioReagent, for cell culture	Suitable for standardized cell culture and post-isolation digestion termination

 

6 Key control points and result interpretation

6.1 Control of digestion strength

(1) Concentration control

If broad-spectrum protease concentration is too high, surface protein loss and membrane damage are likely. If it is too low, residual tissue fragments cannot be effectively reduced.

(2) Time control

Although extending time often improves dissociation, it simultaneously increases the risk of reduced viability, elevated stress, and phenotypic drift.

(3) Temperature control

Temperature directly affects both enzymatic activity and cellular tolerance. For fragile samples, finely controlled incubation time under mild temperature conditions is usually more important than simply increasing enzyme activity.

 

6.2 Coordination with mechanical processing

(1) Degree of mincing

If tissue is not sufficiently minced during pretreatment, later stages often become overly dependent on enzymatic digestion, thereby increasing damage risk.

(2) Pipetting intensity

Excessive pipetting can cause membrane rupture, increased cell debris, and higher doublet rates, and is especially unfavorable for neural tissues and sensitive primary cells.

(3) Filtration strategy

Filtration should serve purification of the single-cell suspension rather than replace earlier digestion steps. If digestion itself is insufficient, filtration alone will cause loss of target cells.

 

6.3 Constraints imposed by downstream use

(1) Flow sorting

It should first be verified whether the broad-spectrum protease affects the recognition epitope of the target antibody.

(2) Primary culture

Attention should be paid to adherence ability, short-term survival, and recovery of proliferation, rather than only immediate viability.

(3) Single-cell sequencing

Single-cell proportion, debris background, aggregation level, and digestion-induced stress effects should be assessed as priorities.

Table 5. Common observations and adjustment directions during optimization of broad-spectrum protease systems

 

Observation	Common Cause	Priority Adjustment Direction
Many residual tissue fragments	Insufficient enzyme combination, insufficient mincing	Prioritize optimization of enzyme combinations and pretreatment
Severe cell aggregation	High DNA release, uneven dissociation	Add DNase I and improve mixing
Marked decrease in viability	Protease too strong or incubation too long	Reduce concentration, shorten time, and decrease mechanical handling
Weakened surface antigen signals	Excessive broad-spectrum protease or trypsin treatment	Switch to a milder system and verify antibody compatibility
Low single-cell proportion	Insufficient loosening of junctional structures	Optimize synergistic conditions between broad-spectrum protease and collagenase

 

The true significance of broad-spectrum proteases in tissue digestion and primary cell isolation lies in improving the completeness of tissue dissociation and the quality of single-cell suspensions through more effective loosening of protein-based junction structures. Their application value does not depend on whether their substrate spectrum is broad enough, but on whether they are matched to tissue composition, synergistic enzyme combinations, and downstream application goals. For most primary isolation systems, the more rational strategy is to treat broad-spectrum proteases as synergistic optimization variables and to combine them with collagenase, DNase I, and appropriate mechanical handling in a finely tuned design, rather than replacing the entire dissociation workflow with a single high-intensity digestion step.

 

For more related articles, please see below:

[1] Commonly Used Proteases in Research: Fundamentals and Representative Applications